TimeMachine’s `tmutil compare` shows lots of files as changed even though there’s been no updates

For example, if I run tmutil compare I see lots of entry like:

+ 42B                           /Applications/Books.app/Contents/Frameworks/BKLibrary.framework/Versions/A/Resources/vi.lproj/InfoPlist.strings + 291B                          /Applications/Books.app/Contents/Frameworks/BKLibrary.framework/Versions/A/Resources/vi.lproj/Localizable.strings + 42B                           /Applications/Books.app/Contents/Frameworks/BKLibrary.framework/Versions/A/Resources/zh_CN.lproj/InfoPlist.strings + 193B                          /Applications/Books.app/Contents/Frameworks/BKLibrary.framework/Versions/A/Resources/zh_CN.lproj/Localizable.strings 

Finder says Books.app was last updated two weeks ago. I have TimeMachine backing up to two drives connected to a Mac Mini, and I connect from my MBP over the house Wifi. Both volumes had a successful backup complete today.

If I force a new backup, it’s reporting 1.4GB has changed despite doing a full back up just a few hours ago, and me only browsing with Chrome and Safari since then.

Why is tmutil listing all these files as changed? and how do I fix it?