I don't think you have to worry about @thunderbird though, Mozilla doesn't seem to care about it at all, they tried to kill it, then get rid of it, eventually just turned it into subsidiary and gave free pass. Thunderbird doesn't even want to use Mozilla account for their sync.
I remember your previous video on Firefox alternatives and the conclusion was "nothing better tbh" and I believe that the only thing that changed since is Mozilla being even worse.

You are right, thunderbird says this:

"Thunderbird operates in a separate, for-profit subsidiary of the Mozilla Foundation. This structure gives us the flexibility to offer optional paid services to sustain Thunderbird’s development far into the future."

@thelinuxEXP @thunderbird

We also wanted to additionally clarify that we won't be adopting the Firefox Terms of Use for Thunderbird, either on desktop or on mobile.