I am not on Mastodon because of Twitter. I’m there because I want to be and have liked it for a long time. I am not into the controversy of who is on or off Twitter or who is running it.
My “joined” date is recent because I’ve had to change instances many times mostly due to them just vanishing on short, or no, notice.
At least now I can have a certain (self-managed) instance for as long as I care to pay for it and the host exists.
Vivaldi Social also looks to be a good pick for longevity.
This is not to deny that there are many strong, reliable, well-managed instances out there. My trust is low because, in spite of being careful, I made one bad pick after another. One even took my donation and shut off the next day without notice. These are issues that I am trying to avoid.