d, g, j, l keyboard keys do not work well after last catalina upgrade

Please help.

I have a 13-inch MBP mid-2012, operating on Catalina 10.15.7. After the last automatic upgrade, the d, f, g, h, j, l keyboard keys do not work properly. I start to type them normally but suddenly they stop working, no matter how many times the keys are pressed. This occurs whether using mac Pages, numbers, TextEdit, or Safari. The problem worsens as I continue typing.

I have tried to follow some of the Apple Support tips, for instance:

- trough Preferences, I verified that slow keys and mouse options are unchecked.

- I turned off the computer, unplugged the power cable, and then turned the MBP on again.

- I also tried to reset the SMC

Unfortunately, no one of these attempts worked. Right now I am writing this note with difficulty as I have to copy individual letters to paste and insert them into incomplete words.

I should add that I am not a specialist and my education level on technical computer issues is limited.

Thanks