Spam filters: what am I missing at this late date?

Last time I checked, it was 2018. We are into our 3rd decade of filtering spam. Why is it still so shockingly terrible?

At work: we use Microsoft/Office 365/Outlook/etc. Every day, at least 2 emails - that I have whitelisted literally 50 times each - show up in the end-of-day spam email summary. How can this possibly be true and what can I do about it?

Gmail: In the past month or so, I've noticed a similar effect...domains that have been coming to me for YEARS are now all of a sudden sent to spam.