My Firefox browser has just updated itself to version 74 and gave a warning that the register site is not using secure protocols. It now expects at least TLS1.2, and I had to give an exception for TLS1.0/1.1. (I trust remembered the correct geek terms?) It indicated that this lower security level will not be supported in future browser updates. I hope you can consider this in future without too much effort.
I am glad I am not the only one with this problem although I do not have the option to override Firefox's decision to block my access. Fortunately I can still use Chrome to feed my habit.