Earlier quoted context omitted.
Oh, bad timing. Just a few months ago I was on the fence about Protonmail vs Fastmail (vs all others) and ended jumping to Fastmail: the privacy pro didn't seem to outweigh the cons. Now with open sourcing stuff the pros do get somewhat better... But reevaluating and switching would be troublesome.... Maybe in a few years I'll revisit it :)
The pricing is very different. Fastmail allows unlimited domains where proton is almost double the cost for two.
Also not providing 20GB space as a default paid option in this day in age of $5/month/TB is also very disappointing.