MP3TAG forums do not allow Firefox 115 ESR to log in, even though it is is scheduled to be developed into 2026.
Can you allow Firefox 115 ESR access, there are machines which cannot install other browsers.
I suspect that the root cause is that your version of Windows is too old.
See Dropped support for older browser versions
I had the same problem, which I solved by installing the Supermium browser, as suggested to me by @Florian. It is a version of Chrome and it works great on Windows 7.
I understand you are saying that MP3TAG forums allow Windows 7/8 as long as a third party browser mod is used on them!?
....but not the official "made by Mozilla" Firefox 115 ESR.... with latest Mozilla security updates... that are more up-to-date than third party browser mods are?
Can moderators consider the fact that modded browsers are made after official browsers are released, so technically in a day or two when Firefox 115.31 ESR is available, it will be more security patched than any of the browser mods that you say work on the forums.
Why not allow Firefox 115 ESR, if less secure browser mods are allowed?
No, it's not supported anymore by the forum software I'm using (as outlined in the other topic).