Keyboard issues -some keys not showing

Since upgrading to Catalina several weeks ago, I am seeing constant issues with typing. The "K" key is one of the worst offenders, but other keys skip and leave blanks or just record the next letter in a sentence. Using default Apple blue tooth keyboard, USB and wireless have same result. ANSI wired keyboard works more reliably. I reset the PRAM last night and it made no difference. I can't type anything without fixing each affected word. Some typing issues existed prior to the Catalina upgrade, but Apple tech was unable to identify a problem.

What causes this and how to fix?