My most recent encounter is pretty much anything to do with Apple Pay (especially on the mac). I couldn't get any transactions to complete. Ended up being that my address didn't validate (apparently) because it was 'too long' -- good luck figuring that out via the (horrific) Apple Pay address form edit UI ...
Ultimately found a work-around by going to the accounts website and adding the new card from a family plan member (which didn't require the last digits of the old on the main account holder's account) and then cahnging the default and deleting the old. But it wasn't documented anywhere.
The handy "google pay" button just sent me on a loop to fix my address, I did, it accepted, then rejected on pay as there was "an issue with my address" - tried 3 times before just nuking my address, re-entering it (I swear the same details) and then it was accepted. Maybe random co-incidence, or maybe common card back-end was having a wobble.
I work with a lot of Mac users and just watching them trying to manage application windows is painful. Ever since they replaced maximize with full-screen - whenever someone wants to click near the top of the window, I make a bet with myself whether they're going to miss the mark and cause the menubar to drop down or not.