It allows third-party keyboards to get full access to the system even if you forbade it.
Third-party keyboards in iOS can be designed to work completely autonomously without access to external services, or they can request “full access” to provide additional functions through network access.
Apple detected an error in iOS 13 and iPadOS, which may result in keyboard extensions being provided Full access is not available even if you did not approve it.
Apple said that the bug will be fixed in the near future. So it’s worth waiting for an extraordinary update.
About an issue that impacts third-party keyboard apps in iOS 13 and iPadOS Update to iOS 13.1.1 or iPadOS 13.1.1 to fix an issue that impacts third-party keyboards on your iPhone, iPad, or iPod touch. support.apple.com