Samsung - Update to Android 10 Changed Keyboard Layout
This is caused by an option for navigation bar with full-screen gestures on Samsung devices with One UI 2.0 (Android 10). The setting can be accessed from Settings - Display - Navigation bar - Full screen gestures - Show button to hide keyboard
According to Gadget Hacks - Enable Android 10's New Gestures on Your Samsung Galaxy with One UI 2,

You can also enable the &quot;Show button to hide keyboard&quot; option so you can switch keyboards at any time when using these new gestures — the keyboard icon appears in the lower-right of the screen.
(Emphasized added)

Based on OP's observation, looks like this option is enabled by default after updating to Android 10.