Not sure if it uncucks your algorithm, but if you go into your watch history you can delete individual videos from the list.

If you go to a particular channel homepage —> about —> click the flag you should see a “block user” option. Also not sure how effective this is.

Another thing is that if it is presented to you on your homepage (pc), there should be a little button that gives you an option like “don’t recommend this channel to me” this one seems to work the best for me, but the problem is you have to wait for it to show up in your recs, so no preemptive blocking (as far as I know)

Edit- I’ve only ever done these in a browser on a pc (tv app just doesn’t have the options)