Thanks for the compliment. Was nice working with you.
I still see the old cert on forum domain about half the time. I'm using the SSL Checker I linked earlier and just click Check a few times. You'll see diff expiration days on repeated attempts.
Did you restart Apache yet? If so, you may need to reboot server.
But it might be the case that I'm using the wrong command. The ways of restarting an apache2 server have changed so often over time (on debian?) I never know which one is the correct one and often settle with apache2ctl restart.
At the link you shared I see no more march 19th anymore. From bottom down to R3 (which isn't on my level anymore) everywhere "not after june 7th 2023". On top it says "89 days until expiration".