Same for the Wiki. Chances are that it's a Daylight Saving Time problem. Chrome just blocks the website. Firefox allows you to continue after showing the error.
FWIW, I'm in Arizona, USA and we don't do DST.
Spoiler:
2021-03-15_10h59_24.png (62.55 KiB) Viewed 12147 times
Old Firefox version didn't allowed the connection at all:
This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox only connect to it securely. As a result, it is not possible to add an exception for this certificate.