Steps to replicate and screenshots of the issue would be helpful.

Thanks for your help... it so happens that back in December Firefox automatically updated to the same version, and I went to one site that displayed the issue. Two screen shots that I shared with them are attached. Some of the affected area is all text, some a mix of photos with text.

I have no issues with the site. see screenshot Did you try with Firefox in Safe Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf

What are your font settings? see screenshot