I noticed bluesky is down.

I haven't seen news about this yet so I wonder if it is just a temporary tech problem or a DOS.

I'm getting this error or an error about rate limiting:

Hmm, some kind of issue occurred when contacting the feed server. Please let the feed owner know about this issue.
Message from server: Upstream server responded with a 503 error

Previously Tildes have had a few discussions on good quality Youtube channels one, two, but I couldn’t find a recent discussion.
I would be interested in peoples recommendations!
Personally I would like to get recommendations for intermediate/harder science or engineering videos. Most are too basic, or very dry lecture based. I know a few good ones like:

• 3blue1brown
• Smarter every day
• Looking Glass Universe

But I would like to know other people’s favourites (including non science ones)!

Just looking for some indication that I'm not going a bit crazy here, but does anyone else get shown videos they've never seen before, indicating that the video has been partially watched?

It seems to be just on search results and recommendations and it picks random points in the video to be kick-off points for continuing.

If anyone has an explanation that'd be appreciated, as it almost feels like my watch history is getting mixed up with someone else's.