Not the person you're responding to, but it appears broken on Chrome and Safari on macOS (Firefox is fine) with a correctly set date. On further inspection it looks like there's a problem with the R3 certificate being expired. After a little Googling and I found this: https://community.letsencrypt.org/t/help-thread-for-dst-root...
I just double checked kozubik.com SSL cert and it expires in 7 days (it is an acme.sh generated certificate, etc.).
Or is Safari complaining about this cert chain ? Genuinely curious ...