For me, it depends heavily on how they do it.

• Will it be FOSS?
• Will of adhere to the ActivePub standard and play nice in not trying to push it around to suit their needs alone?
• Will it be honest about how much and which data they collect, and give users control on how much they want to share?
• Are they good about not forcing their users on an unknowable algorithm?

There's too many factors to decide on a whim. Not all companies are wholly evil like Meta, Microsoft and Elon's enterprises, but they're all for-profit, and we must always be wary. I'm willing to give Tumblr's owner the benefit of the doubt for now.