Steps to reproduce the problem

EDIT: given that this issue is related to the Update PR, I'm not sure there is an easy way to reproduce, see discussion there.
I have not managed to find a way to reproduce since this is happening for me for channels that I was following before the 4.5 update. In theory the following steps should be a reproducer, though it may take a long time:

1. Follow a PeerTube channel with many videos, e.g. https://tilvids.com/c/thelinuxexperiment_channel (optionally activate the bell)
2. Watch a flood of videos appear in your timeline at regular intervals
3. If you activated the bell, watch them flood your notifications

Expected behaviour

Fetched posts (EDIT: or updates) that are older than the current date should not appear in the timeline nor trigger the notifications.

Actual behaviour

They wrongly appear in timeline and notifications.

Detailed description

I cannot guarantee that the problem is linked to the new fetch replies feature but an issue with old PeerTube videos flooding timelines and notifications started happening on my accounts as soon as my instances upgraded to 4.5.
The fact that they appear at regular intervals also seem to also link it to that new feature.
EDIT: combined with the new Update support.

Mastodon instance

scicomm.xyz

Mastodon version

4.5.0

Technical details

No response