I had kind of been meaning to ask of Apple's Mail works these days (after hearing people talk about it on a podcast recently). I had given it up in the mid-2000s when it didn't really work with Gmail boxes. Look like I made a good decision.

(Apple Mail used to be one of my favorite apps.... like so many other apps I've slowly replaced over the years as Apple has ruined them.)
Remember, the 'all time high' thing is Wall Street, which doesn't have a whole lot to do with actual reality.
That said, Apple has been making record profits, but the state of things like this won't show up in the numbers for years.
The fanboys just say, "Oh, you guys just have short memories. Apple has always had their problems and bugs." But, I think my memory is working fine, and they are just seeing things through Wall Street colored glasses.