Maytag washer went from poor spinning to not spinning but rather agitating isntead

I noticed a few weeks ago that my washer wasn’t spinning out water as well as it used to. Additionally, during the agitate cycle I was hearing a weird noise coming from the machine, maybe a banging or knocking. I also noticed that it seemed like when the drum was spinning, the agitator would slow down a tiny bit every few seconds and then get back up to speed to match the drum. I happened to have a spare belt on hand, so I replaced that, but it didn’t help.

Now, instead of spinning during the spin cycle, the drum stays still and the agitator is moving instead.

Where do I look first? Is it possibly the thrust bearing or is my transmission for sure gone? Could it be something else? Any troubleshooting advice is greatly appreciated.