Default value for <AndroidResgenFile> is Resource.designer.cs
https://learn.microsoft.com/en-us/xamarin/android/deploy-test/building-apps/build-properties#androidresgenfile
Two projects were using <AndroidResgenFile>Resources\Resource.Designer.cs</AndroidResgenFile>
All other projects use <AndroidResgenFile>Resources\Resource.designer.cs</AndroidResgenFile>
Difference is one has uppercase D, the other lowercase d
.gitignore already has a rule for 'Resource.designer.cs' in it.
The two projects that were with Resource.Designer.cs needed either a specific line in gitignore
or weren't actually ignored.
Selected fix here is to rename the file with a lowercase 'd' instead of uppercase.
This permits to remove one line from .gitignore and keep the other file really ignored