It is important to remember that as a result of the basic functionality of email, the hard limits of SMTP, email is not secure. You cannot encrypt certain parts of an email, so email providers are always going to have access to those parts of your communications and sometimes nation states can compel providers to collect that information and store it. If you need actually secure communication, email is not the right kind of communication for you.
Protonmail is one of the best free or low-cost privacy tools available, and I find it extremely concerning that the myth of them selling data has persisted. Hell, after they were forced to comply with the request for IP Addresses, they posted a tutorial on how to connect to their servers securely so they couldn't log IPs. I feel like the longer this rumor persists the more people are going to stick with gmail because "oh well, nothing is actually safe anyway, even protonmail sells your data." They do NOT. Open Source and privacy activists continue to stand by Protonmail because protonmail continues to do everything that is legally possible to protect user data and provide encrypted communication.