Characters disappear from text on page

I've been having this problem recently (firefox build 82.0.3 and a few older versions) where characters randomly disappear from the text being displayed. In addition to webpage body text, the address bar and tab titles also disappear sometimes.

As I'm typing this text characters are randomly being replaced with blank spaces. Firefox is the only application on my computer that seems to have this problem. I have restarted it, reset the user profile, and disable all extensions/add-ons in an attempt to debug but it hasn't seemed to help.

Attached are two screen captures, one where the text has disappeared on me and one after I highlighted the text to bring it back. Note: the address bar and tab titles are blank in both since I didn't highlight/click on them.