Unfortunately Linter uses the filesystem modified time rather than when you actually modify a document with Obsidian.
This causes issues when:
- If you copy your vault from one system to another, all of your modified times will update.
- Some sync solutions will also cause the file modified time to update.
- And if you use any external program to change a file it will change the frontmatter property time.
The plugin above will only update the modified date when you actually modify a note using Obsidian. Otherwise I would be using Linter, but sadly it uses the filesystem time 