Chat with Squarespace support:
Me: I have issues with blocks moving randomly.
SS: It's ok on our end, check this video capture.
Me: Look at second 4. It's moving randomly
SS: Oh no, you are wrong. It is supposed to work like that.
Me: Like moving randomly?
SS: yes.
I am about to loose a client because I vouched for using Squarespace instead of Wordpress and now they are mad and frustrated because they cannot edit the site I made. I am never, ever using this platform again.