Looks like a simple and non intrusive and potentially useful feature. Your concern seems unnecessary (for now). They may not be perfect, but they seem to be better than most SaaS companies as far as my experience with them goes. Their web app works, hasnt enshitified or gotten slow, they aren't shoving AI into their stuff afaik. Theyre alright imo for now.
Aside from not having quite as robust an anti-spam approach as gmail (at least at the start), fastmail has been faster and easier to use than gmail was for me, and that's extremely high praise. Even something as obscure as setting a custom color theme for the web UI is fast and painless. I thought getting off gmail would be difficult but it's been a breeze. (not an ad, though it sounds like one)
I have noticed more downtime in the last few months than the previous few years combined. I think they recently did a server migration so hopefully it's not an indication of anything more serious changing in their culture.
