I wanted to share a strange behavior with you regarding hosting. This may or may not be related to the hosting service, but I thought it might be worth mentioning. I used All-in-one migration to extract a single site out of my multisite network. I then spun up a WPMUDEV host instance and imported it. Most pages are not rendering correctly. I'm seeing a bunch of warnings: "PHP Warning: Cannot modify header information - headers already sent in". After trying to get this to work after a couple of hours, I spun up a GCP instance and imported it. Site runs fine with no changes.
I have no idea what's going on, but it may be interesting for you. Something is behaving differently on the WPMUDEV servers. I guess this type of migration (subsite to single site) with All-in-one will probably be fairly common so may be worth looking into.
Let me know if you want to look deeper and I can grant access.