Bug Description:

When an editor with dirty-diff decorations is hidden and shown again (e.g. when switching editor tabs), the dirty-diff decorations disappear.

Steps to Reproduce:

1. Open a file with diff changes in a text editor. Verify that dirty-diff decorations are shown for the changes.

2. Open another editor. Switch back to the first. Note that there are no dirty-diff decorations now.

Additional Information

The issue is present on the current master. It looks like a regression from #14909. I have checked that the issue is present in 72ca8ed, while the parent commit does not have this issue.