The subject says it all.
In the past, several extensions were developed to do what I'm proposing, but every extension developed is now unusable.
This leaves users with the only option to delete ALL caches, but this is overkill for a single site/domain that is not working due to cached content.
Please natively implement a way to delete the cache of a single site/domain.
This is possible using "Forget about this site". https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox#w_clear-cookies...
It is also available on the history sidebar (ctrl + H) or (cmd + H) on MacOS
Thank you Kevin, it seems that your trick is actually working!
Not very intuitive btw, as ppl would expect that hitting "forget this site" in the history sidebar just forgets the history, not cookies+cache+everything.
It does work but you have to keep doing it after awhile. In other words, I think it is the site's servers, not Firefox. On the other hand, the not remembering history option may cause, although when testing this, I didn't notice an improvement. The only other conclusion is that the techies for some sites are pushing the wrong buttons in an effort to minimize hacking, which is useless because you have to be hacked first before you recognize the signatures or methods. It is still an ongoing problem.
My experience with "forget about this site" is that indeed erases everything related to the site.
This looks like it is going to be a constant problem.