the certificate has

Not Valid Before: Wed, 19 Apr 2023 00:00:00 GMT

so it was just created: maybe there are some issue with cache or whatever

Maybe post here the info you see about the certificate

I'm also seeing the notBefore == 19 Apr 2023 00:00:00 GMT.

Maybe they pushed it out a few minutes too early.

Is the time correct on your desktop system?

Seems fine to me. If it's on a desktop your DNS might be hacked, or your time is off?

Off Time is a good catch. I second checking for that. It's caught me before.

DNS hijacks aren't as common as they used to be, but Spyware still replaces your DNS on Windows still to get access to all your traffic.

Sorry for no updates, it is working fine for me, not sure what happened, checked a few minutes later after restarting my PC

It's also possible one of the TLS endpoints in the rotation didn't get the cert update when everyone else did and was serving an expired cert. Then the Reddit SREs noticed it and fixed it before too many people complained.

Damn that was it. I was a little surprised cause everything else worked fine, including HN, Imgur, Google etc.

Is this happening for anyone else?

I'm not seeing anything for the homepage (Firefox, Opera). Let us know what browser you're using. Posting a specific url might help us.

I am trying https://www.reddit.com/

Not seeing issues. Per Xen2xen1, check that your system's date and time are correct.

If that doesn't work, open a command window (in Windows) and do nslookup for www.reddit.com (Linux: open terminal window and do host www.reddit.com).

Let us know what IPs you get back.