Toggling old index format corrupts something

Seeing this for a while now (don't remember when it started though; tested with 1.2-25-debug now)

On Android 6.0.1/8.0.0

What did you do? (clear steps if possible)

1. clean F-Droid data (or install clean)
2. refresh repo
3. toggle GuardianRepo to ON (if it's not already)
4. refresh repos
5. search for Orbot - find the app
6. toggle expert ON
7. toggle old-index format ON
8. refresh repos
9. see the older that current index! 1523012472 < 1523026872 toast
10. toggle old-index format OFF
11. toggle expert OFF
12. refresh repos
13. see the older that current index! 1523012472 < 1523026872 toast
14. toggle GuardianRepo to OFF
15. refresh repos
16. toggle GuardianRepo to ON
17. refresh repos

What did you expect to see?

1. search for Orbot - find the app

What did you see instead?

1. see the older that current index! 1523012472 < 1523026872 toast again
2. search for Orbot - NOT find the app, or any app from GuardianProject
3. you need to clean app data and re-setup all repos/settings

Logcat:

D HttpDownloader: downloading https://guardianproject.info/fdroid/repo/index-v1.jar (is resumable: false)
D UpdateService: Downloading https://guardianproject.info/fdroid/repo/index-v1.jar(0/62117)
D UpdateService: Downloading https://guardianproject.info/fdroid/repo/index-v1.jar(32768/62117)
D UpdateService: Processing https://guardianproject.info/fdroid/repo/index-v1.jar(8000/223156)
E UpdateService: Error updating repository https://guardianproject.info/fdroid/repo
E UpdateService: org.fdroid.fdroid.RepoUpdater$UpdateException: index.jar is older that current index! 1523012472 < 1523026872
E UpdateService:         at org.fdroid.fdroid.IndexV1Updater.processIndexV1(IndexV1Updater.java:234)
E UpdateService:         at org.fdroid.fdroid.IndexV1Updater.processDownloadedIndex(IndexV1Updater.java:156)
E UpdateService:         at org.fdroid.fdroid.IndexV1Updater.update(IndexV1Updater.java:98)
E UpdateService:         at org.fdroid.fdroid.UpdateService.onHandleIntent(UpdateService.java:425)
E UpdateService:         at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:68)
E UpdateService:         at android.os.Handler.dispatchMessage(Handler.java:108)
E UpdateService:         at android.os.Looper.loop(Looper.java:166)
E UpdateService:         at android.os.HandlerThread.run(HandlerThread.java:65)