This has happened to me maybe 15 times in the past month. I'm on Windows 10 Home version 1909. I use Adobe Acrobat Reader DC version 2020-009-20074. I have three different "input methods" (i.e., keyboards, or "preferred languages") set up. When I'm typing inside a comment bubble and press Left Alt + Left Shift to switch between keyboards, Reader often freezes. This doesn't happen every single time, but it does happen frequently. The only solution is to close the program and to start it up again, which often results in loss of recent work.
I have three sets of dump files ready to share. I can link to them here unless doing so will compromise my security. (I don't know what they contain.)
Comment markup and annotate
Crash or freeze