I dumped Proton when Yen blathered about the GOP being better for privacy... Glad I did even though it was disappointing to have to move email addresses again.
For those shopping for email providers, I use Posteo. At the time I was looking at them, AI hadn't quite been shoved everywhere yet so I didn't ask them their policy. https://posteo.de/en
I wrote support to ask what I could tell those who are considering Posteo now about what their AI policy is. This was the reply: