more and more sites, not working on firefox, work on chromium

I'm finding more and more sites no longer work using Firefox. I've confirmed all software is up to date, and tried different settings such as turning off ad , tracker and fingerprinting protections, but nothing works. Even sites at which I have an account have stopped working. Sometimes I can still log in to the account, on others I can't even do that. If I can log in, using the account for what it's intended such as searching for and saving lists of things or following links to saved items doesn't work. I value Firefox for it's security and privacy features, and being able to sync saved information in the account and across devices, but if a site won't all that benefit disappears.