I've only had improvements for my note 10, wish i knew what OP was talking about.

My S10 still gets updates.

I've never actually noticed any difference after almost all of the updates since I purchased it. I'm assuming they either have all been security, "stability" or features that Samsung already had provided in their fork.

I have a few Samsung devices and I'm more than happy with the performance and new features with the updates. It just keeps getting better.

I don't know whether it's correlated with updates, but that's a thing that has happened: https://slashdot.org/story/20/07/01/196224/ads-are-taking-ov...

It's not correlated with updates.

Ironically Samsung Health used to have a little "Ad" banner at the top but after some update that is gone now.