Suddenly, I can't copy and paste text or images using the Firefox browser

Many images on the net are blocked form being copied. It has been a growing trend for a decade. It can be set by the web designer, or other intermediaries. In such a case I do a screen shot if that is possible and edit that to my preference.

It is not the VPN. I get a pop-up window trying to copy text that has a few blank areas and some other functions. I know the blank areas have the copy and cut functions plus other functions because I have selected them and had those functions activate.

I have tried to change the text colors in the Settings in Firefox but have not been successful.

If you're seeing empty items in context menu, reboot your operating system first — that should clear the caches. (Or you can look for Troubleshoot Mode and clearing Startup Cache in the Help menu — more in bugzilla.mozilla.org/2034677)