Glitch has been a key piece of the A-Frame community (open source project I maintain) for almost a decade. I'm super thankful to the team! So many people started programming and had first steps in game and 3d graphics development with Glitch.
It's sad to see it go. I was always somehow worried. They had an awesome and super generous free tier. You don’t even need to create an account! Unfortunately, it looks they couldn't make the numbers work.