There’s a new experience coming to the model-driven app (and dynamics) advanced settings area. I’m not yet comfortable using it as I cannot find all the features I am looking for.
The new advanced settings experience is still in preview: https://learn.microsoft.com/en-us/dynamics365/sales/advanced-settings-new-experience
For some reason, this setting was on by default in one of our customer environments.
To get back the good old advanced settings, you need to go to your Power Platform Admin Center, choose environment, settings and features. Then look for this option:
