~5 years of ProtonMail
Ever since I left Gmail ~5 years ago I have been using ProtonMail's free tier since then. Obviously it's far better than using Gmail or Outloook, but there are some gripes you'll have to deal with.
Protonmail's web interface
The web UI is fairly standard for other popular email clients, as shown above. However it can be fairly annoying to run on non-standard browsers such as Pale Moon, as the frontend is JS heavy. I'm aware that the web client uses Javascript to decrypt messages, but not having a "basic HTML"esque option is rather dissapointing to see. "Just use the bridge and use your own email client!" In an ideal world I'd do that, but for the former I don't have the income right now to manage a subscription. Another minor gripe is that emails can sometimes take several minutes to recive, which is annoying for 2FA shenanigans.
Paywalling organizational features
This is my biggest gripe with the service. You basically can only auto assign 2 email addresses to a tag/folder before ProtonMail tries to railroad you into buying their subscription. This results in me being unable to properly organize my own inbox and having my emails be in one unorganized blob.
Lock in fears
Admittedly this is more of something I've read other people talk about online but since ProtonMail is a private company, lock-in is something to be concerned about in the long run. They've been expanding for the past few years (VPN, cloud storage, etc.), and while that isn't itself bad, they are ultimately are a business doing standard business things, and will face enshittifcation the nanosecond they roll out enterprise contracts. In the future I will probably migrate my email addresses elsewhere or self host.