I want to delete mine too, but I use GMail and I have not found a good alternative yet. Tutanota doesn't have Thunderbird support and ProtonMail has, but only on paid accounts. I really want to use Thunderbird because it is such a great email client.
I was in a similar situation and after a lot of research I found posteo.net and I liked its privacy, FOSS and environmental policies and gave it a try. Happy with its service for just 1€ a month.
I’ve been using Proton for about a year and a half now. It’s been really good for my needs, I started on the free version but then decided to pay to help support them and to get access to everything else (specifically SimpleLogin).
If you're reasonably tech savvy and on linux you can use hydroxide to bridge a free protonmail to thunderbird. I've been doing it for ~a year, I suspect they don't kill it for ratings, but I only have free protonmail on my GrapheneOS phone with forwards from thunderbird for specific things, works great...