Hey at least Chrome lets you can bypass SSL errors. Firefox makes it impossible to bypass SSL errors if the site uses HSTS. So much for the browser for power users.
The TLS errors that aren't unbypassible by specification (i.e. HSTS, see https://datatracker.ietf.org/doc/html/rfc6797) can be bypassed on Firefox just fine. It's only the ones where the spec says bypassing the error shouldn't be possible where Firefox takes a hard stance.
Chrome had to alter their bypass string several times because vendors documented the override rather than fixing their insecure crapware. It makes total sense to me that Firefox does the same.
It is rubbish software, the developers routinely ignore fixing actual bugs in favor of new features, and I wish we had a better alternative that wasn't married to Google.
If you want to set this without using about:config you can go to Settings and search “https” you’ll see “https-only Mode” there and you can turn it on for all windows, private windows oonly or none. There is also an exception list should you want that.