Differences in .meta files do not disappear in Git management for Unity projects

Prerequisites/What you want to achieve

I manage the Unity project at GitHub.
When one of the members reinstalled the source tree and pulled the latest branch, many .meta files, some plug-in files, continue to show differences.
If you discard the difference, pull the latest branch, and then launch Unity, the same difference will continue to appear.
This difference is only made by that member, and there is nothing wrong with the other members.
It would be very helpful if you could lend me your wisdom.Thank you for your cooperation.

My Tools

Unity
GitHub
Git
GitLFS
SourceTree
Firebase
Windows 10

Problems/Error Messages you are experiencing

.png.meta appears in large quantities as shown in the image below.
All the differences are
buildTarget: DefaultTexturePlatform is added.
Not all image files have differences.This difference appears only in the large number of image files where buildTarget:DefaultTexturePlatform did not exist.

In addition, we are experiencing the addition of Firebase Firebase/Plugins/link.xml.