Increasing number of emails not arriving

Starting last year around this time, I noticed that sometimes a website would say they sent me an email (like a verification code or link) but that email would never ever arrive. In the back of my mind I did worry how many OTHER emails weren't arriving, but I took no action other than looking around to check rules (I had none at the time) etc.

More recently it is happening more and more and it is not limited to verification code or link emails. Now it's also like if I sign up for a zoom event and stuff like that. They aren't going to junk or spam or deleted, they just aren't showing up in my inbox. This morning I had to re-register for zooms using my icloud email instead, and that invite came thru just fine.  I've rechecked filters and rules and all that (I have 2 rules now, for substack and beehiiv, which are not the emails not arriving). I have a couple people blocked (again, not related to the emails not arriving). Please help.