As a developer that did many of those migrations, I can claim that it's crystally clear what the problem is.

Storage Access Framework is a framework where user decides which files an app can access and see. That's the API Nextcloud refuses to use.

Old READ_EXTERNAL_STORAGE (replaced with MANAGE_EXTERNAL_STORAGE now) permission gives full access to all shared storage data (where for example DCIM directory with all private photos and their locations lives) without exception or privacy filters like EXIF stripping. This permission was required by many games, malware apps and everyone with 5 minutes of time that could paste that string into the app and refused to allow users to run the app without granting it. It was VERY common to demand access to all storage at startup just to do simple things like download a potential file.

That's the API Nextcloud demands to use and Google is telling them that they can't because they should be using SAF.

Then you tried to say is different than what you wrote. Because giving control to the user is why migration to the new API is actually necessary.

Or you just didn't know the context of what you're commenting on.

So google did nothing with those malware apps and now is doing something with a legitimate, very popular app? It does not compile.

Is nextcloud malware? Yes or no. Why do they treat it as if it is?

They did do something; they introduced a privacy-preserving API to allow users to pick which files the app can access, and only certain apps (file managers, etc) can request the old storage permission and be published on the Play Store.

A cloud sync tool is also a file manager. I don;t know why people act like it isn't.