I know of no FF88 but if it exists, it is too old for updated extensions - they would have been upgraded long ago. How old is your operating system?

Well, until that fated day of 3/14, my addons all worked fine. Issue is thus make them working again. My operating system is W10.

With Windows 10 and FF latest they Addon if they aren't updated to work with latest FF then they will be disabled for security reason. You will have to contact the Addon developer to update their Addon to work with latest version of FF. And as you said you have Windows 10 so why are you still using outdate Firefox as that is a big security hole for malware sites to get to your computer network.

I am not satisfied of Firefox UI and UX in Proton environment, so that's why I remain in Photon. I am aware it is less secured than updating to newer versions, but getting poorer UI and UX should not be acclaimed.

That is why I would like to know how to manually re-enable my add-ons that have been disabled because of the expiration of the root certificate, which Mozilla did not want to update for old versions.

With Windows 10 and FF latest they Addon if they aren't updated to work with latest FF then they will be disabled for security reason. You will have to contact the Addon developer to update their Addon to work with latest version of FF. And as you said you have Windows 10 so why are you still using outdate Firefox as that is a big security hole for malware sites to get to your computer network.

This is not the reason for the Extensions being disabled as the reason is explained in https://support.mozilla.org/en-US/kb/root-certificate-expiration