I think it's a question of philosophy. If I take donations for something, is it really still my hobby projects I build in my free time?

Not really IMO. The moment I make money off it, it's more than that.

And if I have a community of people who use that project, I should be transparent with them and engage with them. Maybe the Lemmy devs are doing this in some place where I'm not (like on their matrix), but I have never seen them explain why they are working on certain features and not on others. Their development updates are awesome and I appreciate them, but it's very much a communication of "we are doing this, see you next time". The recent AMA was a good example of engagement that gives the possibility to explain things better and get into contact. My advice would be to work on communication and feedback channels.

But everyone is free to see that differently.