40 notifications when last seen notification id is invalid

[sk22]

mastodon will sometimes display a notification badge with "40" - i'm assuming that's because the last seen notification ID might not be in the list of notifications anymore, e.g. when a follow request gets replaced by a "person followed you" notification. i can reproduce it like this:

• request to follow my account from another account
• make sure i've seen the notification and cleared the notifications badge
• accept the follow request (from another app)
• re-open mastodon for android
• see the notification badge show a "40"