There is no expiration date or such for a Firefox version.

Windows 7, 8, 8.1 is still currently being supported with Firefox 115 ESR for security fixes (and stability, no new features) as the current is Fx 115.18.0esr and Fx 115 ESR will be supported till at least Fx 115.21.0esr in March 2025 unless Mozilla decides in early 2025 to extend updates support again. https://support.mozilla.org/en-US/kb/firefox-users-windows-7-8-and-81-moving-extended-support

The old Firefox 94.0.1 released back on November 4, 2021 is behind on many security updates including critical security fixes.

From your thread /questions/1480108 you posted as a reply

Hi James Your reply does not answer my question - "Could you please advise a work-around to allow me to continue to use Firefox V 94.0.1 reliably after 25 March 2025". Thank you. Also FYI, I indicated that I was continuing to use Firefox V 94.0.1 (64-bit) on Windows 7 Professional. This is because all versions later than 94.0.1 modified settings which had to be reset after an update. This was not necessary up to and including V 94.0.1 Cheers Graham Garden

The issue in March 2025 is Extensions you have installed may not work after March 14, 2025 unless you have Firefox 128 or later or Firefox 115.13.0esr or later as explained in https://support.mozilla.org/en-US/kb/root-certificate-expiration