This has been happening for many months, so it's not limited to 1.18.

Keystrokes will suddenly start becoming random. The keystroke changes each time I press a key. Even the same key will cause different things to happen.

Closing the game AND launcher solves the problem (every time but once, but that was probably just two back-to-back occurrences).

Today I noticed it while outside the game, typing in Word (with the game running in the background). But, closing the game and launcher corrected the problem in Word as well.

So, this problem has just become quite a bit more severe.

Many people have reported this happening to them, so it's not very likely it's a keyboard or computer issue. It seems more likely that the game is overwriting Windows' keyboard interface or something like that.