I have the exact same problem, also on Macbook Pro but with one external 27inch. After reading your post I started fiddling around with the Work Environment settings again, and found a possible temporary solution. In the "Advanced Redraw Options" under "Work Environment" I set the "2D Drawing Acceleration" slider to Off. This solved the problem for me. I did this many times to make sure, and each time I set it back on, the letters started disappearing again. Maybe this will work for you also.
Previously, during the Beta period, we found this problem to be solved. Our colleague tested this again, and surprisingly, it is still happening in Update 2. Thus, we made a new defect entry for it (DEF-6761). I hope that we will be able to address it soon.
Thank you very much for your understanding, and once again, I'm so sorry for the troubles that this defect is causing!
Just chiming in to say same issue here on 2019 MBP with 2 external monitors on V25 4013. It's really distracting while working as the appearance is consistent with a drafting mistake that we are all trained to be on the lookout for. The workaround suggested by @burgersw fixed it for me but comes at the expense of performance. This is currently my highest priority bug. Looking forward to the fix.
Nattering nabob of negativism 2019 MBP (2022 MBP M1 still in the box)