Here is a list of what was fixed since 11.5.16:

• 2022-10-11 c9d6312b60 [RELEASE] Release of TYPO3 11.5.17 (thanks to Benni Mack)
• 2022-10-11 c4dd98c8d7 [BUGFIX] Ensure case-insensitive like() and notLike() expression (thanks to Stefan Bürk)
• 2022-10-11 871d71b248 [BUGFIX] Avoid undefined array key access with 'nonWrappedTag' (thanks to Christian Kuhn)
• 2022-10-11 b914a35e2f [BUGFIX] Avoid undefined array key access in explodeUrl2Array() (thanks to Christian Kuhn)
• 2022-10-11 e6b8917d97 [TASK] Replace prophecy in PreviewModuleTest (thanks to Anja Leichsenring)
• 2022-10-11 5f898be499 [BUGFIX] Prevent undefined array index "pi_flexform" (thanks to Simon Schaufelberger)
• 2022-10-10 43c7ada342 [BUGFIX] Avoid notices triggered by invalid markup (thanks to Georg Ringer)
• 2022-10-10 3990e8a6e9 [BUGFIX] Ensure DB Check->Full Search module works with PostgresSQL (thanks to Stefan Bürk)
• 2022-10-10 e911f029b7 [BUGFIX] Avoid undefined array key access in TextMenuContentObject (thanks to Stefan Bürk)
• 2022-10-10 f9d78df7e8 [BUGFIX] Ensure proper identifier quoting in AbstractMenuContentObject (thanks to Stefan Bürk)
• 2022-10-10 d8b2c8d2f6 [BUGFIX] Ensure working PostgreSQL libpq version environment check (thanks to Stefan Bürk)
• 2022-10-10 275677e2e4 [BUGFIX] Uninitialized properties in DebuggerUtility (thanks to Mario Lubenka)
• 2022-10-10 3a5f6faf92 [BUGFIX] Ensure ext:redirects backend module pagination works (thanks to Stefan Bürk)
• 2022-10-09 d05ada74ec [TASK] Replace prophecy calls in AdminPanelInitiatorTest (thanks to Anja Leichsenring)
• 2022-10-09 0032537898 [BUGFIX] Properly cleanup registered exception handlers in tests (thanks to Stefan Bürk)
• 2022-10-08 6962acffc9 [TASK] Ensure unit tests properly call parent::setUp() (thanks to Stefan Bürk)
• 2022-10-08 ccd255d0d8 [BUGFIX] Avoid undefined array key access in PageInfoViewHelper (thanks to Stefan Bürk)
• 2022-10-07 4e1fec7e4a [TASK] Update to PHPStan 1.8.8 (thanks to Oliver Klee)
• 2022-10-06 438a186a3f [BUGFIX] Always call GU::intExplode with a string in EXT:frontend (thanks to Oliver Klee)
• 2022-10-04 ba5b51e4aa [TASK] Prevent undefined array key warnings in ext:filelist (thanks to Oliver Hader)
• 2022-10-04 9a3832ee36 [TASK] Tune php-cs-fixer setup (thanks to Christian Kuhn)
• 2022-10-04 ce5cbc5057 [TASK] Update to PHPStan 1.8.7 (thanks to Oliver Klee)
• 2022-10-04 2c9bd5085f [TASK] Mitigate browser "spell jacking" in form elements (thanks to Oliver Hader)
• 2022-10-04 b6508ae04a [TASK] Raise friendsofphp/php-cs-fixer:^3.11.0 (thanks to Christian Kuhn)
• 2022-10-03 ad512c971d [BUGFIX] Avoid possible notice in AbstractPlugin (thanks to Georg Ringer)
• 2022-10-03 ac33275994 [TASK] Enable one TransportFactory unit test execution for PHP8.1 (thanks to Stefan Bürk)
• 2022-09-29 ad2d8405b2 [BUGFIX] Prevent undefined array key in TimeTracker (thanks to Daniel Siepmann)
• 2022-09-29 11b19e3344 [BUGFIX] Handle missing pageRow in DatabaseRecordList (thanks to Markus Klein)
• 2022-09-29 f256347ef3 [TASK] Purge FormProtection in some functional tests (thanks to Christian Kuhn)
• 2022-09-28 167533731b [TASK] Remove last usage of t3x (thanks to Georg Ringer)
• 2022-09-27 3f3b32c382 [BUGFIX] Consider filemounts from groups (thanks to Christopher Schnell)
• 2022-09-26 04b04f4298 [TASK] Add base64url encode/decode functionality (thanks to Oliver Hader)
• 2022-09-23 ac1703aeb8 [BUGFIX] Restore and streamline auth log with MFA (thanks to Susanne Moog)
• 2022-09-23 a9d1d69261 [BUGFIX] Fix glitches in controls of EXT:viewpage (thanks to Andreas Fernandez)
• 2022-09-22 518db50d0b [BUGFIX] Show correct group label for system records (thanks to Markus Klein)
• 2022-09-22 394d30a8a4 [BUGFIX] Prevent undefined array key in ProcessedFile (thanks to Daniel Siepmann)
• 2022-09-22 a05f943265 [BUGFIX] Prevent failed property access in PublicPropertyDeprecationTrait (thanks to Daniel Siepmann)
• 2022-09-22 defedd2d77 [BUGFIX] Prevent undefined array key in AbstractItemProvider (thanks to Daniel Siepmann)
• 2022-09-22 7e5c9ed19a [BUGFIX] Render proper markup for datetime picker buttons (thanks to Andreas Fernandez)
• 2022-09-22 2f70b7a174 [BUGFIX] Prevent undefined array key in SaveToDatabaseFinisher (thanks to Oliver Bartsch)
• 2022-09-22 1e6d54e02a [BUGFIX] Prevent undefined array key in SearchController (thanks to Oliver Bartsch)
• 2022-09-22 234547285d [TASK] Prevent undefined array key warnings in ext:adminpanel (thanks to Oliver Hader)
• 2022-09-22 209c3b387d [BUGFIX] Streamline Changelog documentation tags (thanks to Christian Kuhn)
• 2022-09-21 eb96ea2d37 [BUGFIX] Prevent undefined array keys in AbstractMenuContentObject (thanks to Oliver Bartsch)
• 2022-09-21 627772477f [BUGFIX] Use values for link types (thanks to Oliver Bartsch)
• 2022-09-21 f24de0da6e [BUGFIX] Allow sorting of pages on root level (thanks to Frank Naegler)
• 2022-09-21 07a7e335f7 [BUGFIX] Disable horizontal scrollbar in module menu (thanks to Andreas Fernandez)
• 2022-09-21 1ca828acb8 [BUGFIX] Update missing file properties (thanks to Daniel Siepmann)
• 2022-09-21 56198c2557 [BUGFIX] Don't ignore TCA 'ctrl' 'groupName' (thanks to Christian Kuhn)
• 2022-09-20 a5fd2a7197 [TASK] Remove unused configuration option (thanks to Benni Mack)
• 2022-09-19 7ab6610d9e [TASK] Prevent undefined array key warnings in ext:beuser (thanks to Oliver Hader)
• 2022-09-19 49006d966c [TASK] Prevent undefined array key warnings in ext:dashboard (thanks to Oliver Hader)
• 2022-09-18 7117ba700d [BUGFIX] Guard array key access in TypoScriptFrontendController (thanks to Stefan Bürk)
• 2022-09-18 c82290c39c [BUGFIX] Avoid undefined array key access in HtmlParser (thanks to Stefan Bürk)
• 2022-09-16 e65775390c [BUGFIX] Fix hide/unhide inline control for a special case (thanks to Nikita Hovratov)
• 2022-09-16 bc3d79e20b [DOCS] Clarify the page TSconfig settings for RTE (thanks to linawolf)
• 2022-09-16 dc105e348a [TASK] Streamline scheduler flash messages (thanks to Guido Schmechel)
• 2022-09-16 2861cbb5d4 [TASK] Remove wrong doc comments in \TYPO3\CMS\Core\Database\Connection (thanks to Torben Hansen)
• 2022-09-16 3df0079218 [BUGFIX] Use array key access guard in WorkspaceVersionRecordsCommand (thanks to Daniel Siepmann)
• 2022-09-16 99a1a5d047 [TASK] Allow flushing the makeInstance class name caches for testing (thanks to Oliver Klee)
• 2022-09-16 89e93da2a6 [BUGFIX] Avoid FE error if url field on external pages is empty (thanks to Marc Willmann)
• 2022-09-16 58b6a5befb [BUGFIX] Use array key access guard in WorkspaceVersionRecordsCommand (thanks to Daniel Siepmann)
• 2022-09-16 bbeb1ea773 [BUGFIX] Use array key access guard in SchedulerCommand (thanks to Daniel Siepmann)
• 2022-09-16 1f7cd867c3 [TASK] Add note about the Testing app context (thanks to Markus Klein)
• 2022-09-16 26d15e3e80 [BUGFIX] Avoid undefined array key in RecordLinkHandler (thanks to Kevin Appelt)
• 2022-09-16 48911e043c [TASK] Simplify BackendUserGroupRepository::findByUidList (thanks to Oliver Hader)
• 2022-09-16 2a348bedea [BUGFIX] Use array key access guard in ExtensionManagementUtility (thanks to Daniel Siepmann)
• 2022-09-13 f1e23cd7f4 [TASK] Set TYPO3 version to 11.5.17-dev (thanks to Oliver Hader)