Here is a list of what was fixed since 11.5.9:

• 2022-05-10 1fce0e5158 [RELEASE] Release of TYPO3 11.5.10 (thanks to Oliver Hader)
• 2022-05-10 91f7464012 [TASK] Raise typo3/testing-framework:^6.16.4 (thanks to Christian Kuhn)
• 2022-05-09 eb3875a138 [TASK] CI: Always retry failed jobs once (thanks to Christian Kuhn)
• 2022-05-09 617ca91d60 [BUGFIX] Fix undefined array key warning in DataHandler (thanks to Nikita Hovratov)
• 2022-05-09 68704bd654 [BUGFIX] Avoid calling string functions with non-strings in GU (thanks to Oliver Klee)
• 2022-05-08 57f36963a4 [TASK] Ignore PHPStan errors in GeneralUtilityTest for contract violations (thanks to Oliver Klee)
• 2022-05-08 8087bf5ba6 [DOCS] Correct grammar in a Changelog ReST file (thanks to Lina Wolf)
• 2022-05-07 67ed498581 [TASK] Resolve "right side of && is always true" in PHPStan (thanks to Larry Garfield)
• 2022-05-07 79ebd0e63d [BUGFIX] Avoid postgresql error previewing a fe_group-protected page (thanks to Stephan Großberndt)
• 2022-05-07 91829c491c [BUGFIX] Correct type annotation of GU::callUserFunction() (thanks to Andreas Fernandez)
• 2022-05-07 c47479873a [TASK] CI detection in runTests.sh for phpstan (thanks to Stefan Bürk)
• 2022-05-07 d52d725881 [BUGFIX] Pin CI image docker:20.10.14-dind (thanks to Christian Kuhn)
• 2022-05-06 ff8c957251 [BUGFIX] Remove "overflow: hidden" from form-wizards-element (thanks to Nikita Hovratov)
• 2022-05-05 d09bec9242 [TASK] Add username to password recovery email salutation (thanks to Patrick Lenk)
• 2022-05-05 77253e4035 [TASK] Simplify a condition in the workspaces DataHandlerHook (thanks to Oliver Klee)
• 2022-05-05 d77c96608a [TASK] Raise phpstan/phpstan:^1.6.7 (thanks to Stefan Bürk)
• 2022-05-04 f2e4e83808 [BUGFIX] Avoid returning invalid return type in AbstractOEmbedHelper (thanks to Florian Rival)
• 2022-05-04 68c9b545ef [BUGFIX] Name invalid identifier in UpgradeWizard exception (thanks to J. Peter M. Schuler)
• 2022-05-04 4ed1f2ede9 [BUGFIX] Fix several type annotations in FormDefinition (thanks to Elias Häußler)
• 2022-05-04 3ba1b87f31 [BUGFIX] Allow backend layout without any colPos (thanks to Kevin Appelt)
• 2022-05-04 f1095c5fb1 [BUGFIX] Detect arm64 and switch selenium docker image (thanks to Jochen Roth)
• 2022-05-04 e6acc0b8ac [TASK] Add unit tests for mailto_makelinks (thanks to Simon Schaufelberger)
• 2022-05-04 fa95b8af2c [DOCS] Adjust removal version of switchable controller actions (thanks to Chris Müller)
• 2022-05-04 635916bcb2 [BUGFIX] Fix namespaces in extension scanner files (thanks to Oliver Bartsch)
• 2022-05-03 97798c066c [BUGFIX] Correctly resolve instance script path (thanks to Oliver Hader)
• 2022-05-03 6b71fb46d7 [BUGFIX] Apply workspace context in FileRepository::findByRelation (thanks to Oliver Hader)
• 2022-05-02 742f4f03a3 [BUGFIX] Remove invalid definition of method body functionality (thanks to Simon Schaufelberger)
• 2022-05-02 953687bf8a [BUGFIX] Avoid unreliable 'rowCount()' in IndexSearchRepository (thanks to Stefan Bürk)
• 2022-04-29 4b16b3c95c [TASK] Streamline form element labels in form editor (thanks to Elias Häußler)
• 2022-04-29 3955aa9110 [TASK] Raise symfony/rate-limiter:^5.4.8 and re-enable tests (thanks to Torben Hansen)
• 2022-04-29 431a630308 [BUGFIX] Fix type warnings in the workspaces CommandMap (thanks to Oliver Klee)
• 2022-04-28 dc9abf5991 [TASK] Update PHPStan to 1.6.3 (thanks to Tymoteusz Motylewski)
• 2022-04-28 335ceaff6a [DOCS] Restructure API Reference (thanks to Björn Jacob)
• 2022-04-28 8e7aeb56ff [BUGFIX] Correct several typos (thanks to Stephan Großberndt)
• 2022-04-28 a12b3201fa [BUGFIX] Use the correct pluralized key in search results (thanks to Larry Garfield)
• 2022-04-28 55d3fce3da [BUGFIX] Apply initial value to additional form element property paths (thanks to Ralf Zimmermann)
• 2022-04-28 9cdfa70c0f [BUGFIX] Adopt doctrine/dbal sqlite autoincrement detection (thanks to Stefan Bürk)
• 2022-04-27 d492a4eed2 [BUGFIX] Raise phpstan processTimeout (thanks to Stefan Bürk)
• 2022-04-27 b8211b2f15 [TASK] Update composer v2 error message in runTests.sh (thanks to Stefan Bürk)
• 2022-04-27 aecc6c35bc [BUGFIX] Add maxwidth / maxheight parameters to YouTube oembed url (thanks to Oliver Bartsch)
• 2022-04-26 0e67a246a1 [DOCS] Fix typo in "Feature: #94996" (thanks to Nikita Hovratov)
• 2022-04-26 e784c91247 [BUGFIX] Prevent undefined array key warnings in PageRenderer (thanks to Oliver Bartsch)
• 2022-04-26 0941c67453 [TASK] Update PHPStan & friends (thanks to Oliver Klee)
• 2022-04-26 15cae09b00 [BUGFIX] Prevent undefined array key warnings in FormEngine (thanks to Oliver Bartsch)
• 2022-04-25 f96a1d9e7e [TASK] Add runTest.sh -s clean to remove build related files (thanks to Stefan Bürk)
• 2022-04-25 b3a61c3969 [BUGFIX] Fix uninitialized string offset in TypoScriptParser (thanks to Oliver Bartsch)
• 2022-04-25 86e847cdf3 [BUGFIX] Fix undefined array key warning in TcaInline (thanks to Oliver Bartsch)
• 2022-04-25 909e2ad9a9 [BUGFIX] Check parsed option in EmailFinisher (thanks to Oliver Bartsch)
• 2022-04-25 b5b82bbbd1 [BUGFIX] Handle sorting of paginated FileList properly (thanks to Oliver Bartsch)
• 2022-04-25 d6782a1dde [BUGFIX] Avoid unreliable 'rowCount()' in RedirectRepository (thanks to Stefan Bürk)
• 2022-04-25 032461e78a [DOCS] Fix ImageUpload YAML code (thanks to Malte Koitka)
• 2022-04-25 f0c72fb1e6 [BUGFIX] Fix the generics annotations of ObjectManager (thanks to Oliver Klee)
• 2022-04-25 1a72530bee [BUGFIX] Fix the generics annotations of makeInstance (thanks to Oliver Klee)
• 2022-04-25 f3ce89740f [TASK] Add runTest.sh support for more MariaDB and PostgreSQL versions (thanks to Stefan Bürk)
• 2022-04-22 23c553784e [BUGFIX] Keep schema in http_makelinks (thanks to Achim Fritz)
• 2022-04-22 5d3e6abbd8 [BUGFIX] Fix sorting of file properties in FileList (thanks to Oliver Bartsch)
• 2022-04-21 5a147005fd [BUGFIX] Prevent undefined index warning in FileListController (thanks to Daniel)
• 2022-04-20 2ebabf7aa1 [TASK] Additionally removes dangling docker volumes with runTests.sh -u (thanks to Stefan Bürk)
• 2022-04-20 447c7e700b [BUGFIX] Reference labels to input fields in ext:setup (thanks to Torben Hansen)
• 2022-04-20 cd53c3e9d9 [BUGFIX] Avoid undefined array key warnings in ImageContentObject (thanks to Nikita Hovratov)
• 2022-04-19 af866543c1 [TASK] Update minimum PHP version in install tool check (thanks to Oliver Bartsch)
• 2022-04-19 6402d16cf8 [BUGFIX] Responsive form actions for column selector (thanks to Nikita Hovratov)
• 2022-04-18 1a8f97b216 [TASK] Migrate form-horizontal class to Bootstrap 5 (thanks to Nikita Hovratov)
• 2022-04-17 905058d9e0 [BUGFIX] Fix an incorrect type annotation in the DataHandler (thanks to Oliver Klee)
• 2022-04-17 7bd0e3a44f [TASK] Update PHPUnit & friends (thanks to Benni Mack)
• 2022-04-17 591a2ff99a [TASK] Annotate nullable properties in workspaces extension as such (thanks to Oliver Klee)
• 2022-04-16 1d504448df [BUGFIX] Respect workspace in ajax slug generation (thanks to Imko Schumacher)
• 2022-04-16 e588db7b3e [TASK] Add a code of conduct document (thanks to Oliver Klee)
• 2022-04-16 ca959bb6b2 [TASK] Raise PHPStan to version 1.5.6 (thanks to Benni Mack)
• 2022-04-15 0e68937452 [BUGFIX] Fix type annotation of HistoryService::differencesObject (thanks to Oliver Klee)
• 2022-04-14 c51091f763 [BUGFIX] Prevent PHP warnings in workspace ActionHandler (thanks to Oliver Bartsch)
• 2022-04-14 3cc948b14e [BUGFIX] Prevent PHP warnings in PageRouter (thanks to Oliver Bartsch)
• 2022-04-12 0d04df7f08 [DOCS] Rename undeclared argument "length" to "maxCharacters" (thanks to Eric Bode)
• 2022-04-12 ede0f3b2aa [BUGFIX] Add missing tooltips in record and filelist (thanks to Oliver Bartsch)
• 2022-04-12 b00e89128b [TASK] Set TYPO3 version to 11.5.10-dev (thanks to Oliver Hader)