Yes, it should do that. There’s no live connection between the schematic and the layout. You can open them independently and even when they are both open in the same project they are independent internally. All communication between them must be explicit. Therefore it doesn’t matter if you change one file, even make it garbage, until you try to sync them.
This is why I said that all changes should be small and simple before you update one file from the other. If you do changes (component changes) in both, save them and then try to update in one direction, you may get into problems. Or if you make several kinds of changes in the schematic – add new components, change annotations, replace symbols with new ones – before updating the layout you may be in trouble.
In more complicated cases it’s also important to understand how connections between schematic components and layout components are made. That’s what you noticed already. Read Update PCB from Schematic's match methods. (EDIT: here’s another explanation: kicad pcbnew duplicate reference designations (#4012) · Issues · KiCad / KiCad Source Code / kicad · GitLab .)