While some clients are fine (Edge on Win10) by Firefox on Win10 gives a certficate revoked error and SSLLabs gives a grade F saying it is revoked by r3.o.lencr.org
As for why it's revoked (or why it's still serving a revoked certificate), well I can't answer that. But it is definetly something the site operator has to fix (the certificate was revoked about 3 weeks ago).
[Another interesting find: There is a new certificate for that domain, here, issued by DigiCert, but it is apparently not served by the server(s). The site operator may have intended to replace the LE certificate with this one, but failed to do so]
It is? crt.sh disagrees: crt.sh | 5272338295 OCSP is "good", CRLs say "Not revoked"? Manual OCSP also says "Good". Or do I not understand your post correctly?
Or did they change the certificate in the last few hours? That's sneaky! crt.sh | 5058682248 is revoked indeed.