Proton left Mastodon...

If you're looking to shake up your email provider in the wake of this, I highly recommend getting a custom domain name, whatever provider you choose. Cloudflare sells domains at cost. Get a not-embarrasing .com of your own, and then you can move email providers in future without losing continuity. Proton allows exporting .eml files, which you can then import into your next provider. Or just keep in cold storage and declare email bankruptcy. Once you have a custom domain, you can use unique emails for all your services by setting up a catchall address. This will at least impede credential stuffing attacks, and let you know who sold/leaked your address if you do get spam.

I personally left Proton a month or so ago after the last bit of drama, in part out of principle, but also because their offering is just really expensive for my use case: I just want email, on a budget, with reasonable privacy. Plus I was tired of not having IMAP support and being locked into their clients. Moved to a Zoho business account (for now) and have been happy for the $12/yr. I already had a domain name, but they typically run <$20/year too.