Unity deletes files itself from my asset folder on Mac OS - firebase

Question

I've got a problem with Unity installed on Mac OS (Unity 2020.1.16f1 Personal and Mac OS Catalina 10.15.6)
It's look like Unity delete files by itself from my asset folder.
It occurs with both a Firebase (Firebase SDK 7.0.2) and PNG file.
The deletion seems to occur something like each hour (more or less)
However the problem don't happen with all my assets, for exemple with the Firebase SDK it seems that only the file FirebaseCppApp-7_0_2.bundle (and with my png file it happens only with a specific file).
Here's how I get the problem (exemple with Firebase SDK):
I import Firebase SDK I need into Unity (Import Package -> Custom Package and then choose the one I need)
Got this error: "DllNotFoundException: FirebaseCppApp-7_0_2"
Correct this error by going to Security And Confidentiality of my Mac and authorize Firebase to be open (when you download something from internet directly sometimes your Mac ask for this authorization because he don't recognize the developer)
Work perfectly for approximately 1 hour (I can make all changes I want, test my game with the game mode etc ...)
After 1 hour get the error of 2) again (on game mode)
I can fix the problem by reimport only one file from the SDK (FirebaseCppApp-7_0_2.bundle locate in Assets/Firebase/Plugins/x86_64/)
The first time I click play in Game Mode Unity crashes
Go to 3) step and continue
Is someone already get this error ? I've found multiple thread on internet talking about similar bugs (but not exactly the same) but nothing worked for me ...

Answer 1

I found and correct the problem. In fact the problem came from the iCloud which seems to not works correctly with Unity. For some obscur reason, the files which were deleted didn't sync with iCloud, and so when iCloud sent back the project the files were missing. You need to disable automatic sync with iCloud.

Answer 2

Some earlier versions of the Firebase SDK offered to add packages to the Unity Package Manager and would migrate files automatically. I would suggest using only unitypackage integration and trying to undo this migration in the process now. To see if this is the issue, do the following:
close Unity
open Packages/manifest.json and delete the entry for "ScopedRegistries" and remove any lines under "dependencies": { that start with "com.google. Note that Packages is a sibling of Assets (that is, it's next to rather than inside).
for safety, remove any Firebase packages under Assets. This include the folders:
Assets/ExternalDependencyManager, the (old) Assets/PlayServicesResolver, Assets/Firebase, Assets/Parse, Assets/Editor Default Resources/Firebase, Assets/Plugins/Android/Firebase, and Assets/Plugins/iOS/Firebase.
Download the latest Firebase Unity SDK (you can check the release notes here).
open Unity again and add each UnityPackage you need from the SDK. You can usually follow the errors in the console output if you've forgotten everything you're using.
A less likely issue you might be running into is MacOS's stricter behaviour with respect to gate keeper. There's a video here with a workaround, but since you mention the PNG files disappearing I expect that it's the External Dependency Manager.