It's definitely happening when I'm getting updates from lemmy.world, and while I don't know how to get at the HTTP details you're showing in your video, I do see a lot of 400's in the nginx log from Docker:

proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 200 0 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 400 62 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 400 62 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 200 0 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 400 62 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 200 0 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 200 0 "-" "Lemmy/0.19.3; +https://lemmy.world"
proxy-1  | 135.181.143.221 - - [13/May/2024:23:03:43 +0000] "POST /inbox HTTP/1.1" 400 62 "-" "Lemmy/0.19.3; +https://lemmy.world"

Cool, thanks, I'll either wait for a new release or take a stab at building/deploying myself at some point.

Old posts aren’t federated. As new posts roll in, they’ll start appearing.

Oh, that makes sense, and explains why I have content from the ones I subscribed to a couple of days ago but not the ones I just added. And your reply showed up on my server, and I'm posting and replying from my server, so things do seem to be flowing.

I setup my lemmy log to go to a file as opposed to the console. Then it’s searchable, archiveable, etc.

Yeah, I was going to look into doing that as well. Are there any docs on how to do it, or is it something you did at the Docker level?