Sent them a bug report. Thanks.
Also, for anyone else that also has this problem, I found an older thread from 2020 that seems to have the exact same problem (not sure if they’re also using Addressables), and they found another good workaround. When you open a prefab, there’s another Autosave option, separate from the one in Preferences, that you can disable. It is located here. Disable that, and it will no longer save and trigger the asset reimport issues every time you make a change.
This isn’t a solution to the main problem, which is that modifying one singular prefab causes a reimport of all prefabs, but it will at least reduce the problem to only having to do it once when you decide to save your changes.