I live in a house converted into studio flats and we have two communal washing machines in the basement. Landlord/lettings agency have made the decision to stack one on top of the other. Everything I've looked at says this is a bad idea! https://dependablelaundry.com.au/cant-stack-washing-machines/#:~:text=Trying%20to%20install%20a%20washing,potentially%20causing%20it%20to%20topple.
Australian website, but you get the idea.
They've been boxed in as well (something to do with the council and fire brigade suddenly having a problem, despite them originally saying it was fine) but even with that the one on top hasn't been secured to anything. It's just been sat on top of the other one. (It's also been out of order since December, despite being brand new, but that's another rant!) They've basically built a big cupboard around these machines.