MacBook Pro keeps typing z & has intrusive Eastern European font dialogue box partial solution?

Macbook keeps typing a z & has intrusive Eastern European font dialogue box

this is identical to a 2016 & 2017 problem partially addressed in apple discussion thread #7624995.

screenshot enclosed:

a few weeks after an OS 12.6.1 upgrade on a Macbook Pro mid 2015....

1. on any open field (spotlight search window, web browser search window, notes, word, log in pages) the laptop auto types the letter z repeatedly with some pauses and some rapid and lengthy bursts
2. the delete key sometimes works and sometimes adds more z's
3. all other keys & functions work

4. sometimes a small dialogue box appears with three eastern European language font versions of the letter Z. Under each of the three z's is the number 1 2 or 3 as shown above in the screen shot. (Ukrainian, Polish, Czech and Serbia are commonly associated with those languages.) .

somethings that did not work:

restart, restart in safe mode, update browser, extensions & OS, guest user, SMC reset, PRAM reset, cache clear, update & run antivirus, some combo of these repeated.

somethings that did work:

1) set the keyboard in system pref from weirdly defaulting from the normal internal keyboard setting to a nonexistent bluetooth keyboard by.....

 system pref—>keyboard—>modifer keys—>select keyboard —>toggle from  ‘bluetooth usb host controller’ to  ‘apple internal keyboard/tackpad”  —> ok

this will work for a while then the " bluetooth usb host controller" will default back on and the highly intrusive z auto typing will resume. you can repeat for short term fix or ...

2)What seems to work for several hours so far is to set the accessibility keyboard to "enable full keyboard access" by.....

system pref—>accessibility-->keyboard--> check the box "enable full keyboard access"

[Re-Titled by Moderator]