They keep stretching the definition of "compact". There's new oceans (maybe it's climate change) of whitespace between various elements. There's less contrast (none, AFAICT) separating what are clearly different zones, eg the sidebar vs the email content. The default font is atrocious (for email).

There is a single good thing. They re-promoted a top level button from ages ago, mark unread. It's in a "section" with the new snooze button. Quoted because you almost cannot tell it's a section. Did you notice it's segregated from the sections to either side with tiny essentially invisible bars?

I could go on for pages, and oh how I would love to, but that isn't my main point.

I find I hate almost all UI changes of newly updated products. But surely, these are big companies and they absolutely must do A/B user testing, right? Who in their right mind likes these changes?!?!? Is it some kind of job security for UI/UX people? How do they get away with it? It just reeks incompetence to me, I don't get it. Just look at iTunes' evolution for another prime example.

Or, am I just change averse?

Let me also point you to literally my favorite website, https://grumpy.website/