Honestly, I don’t have as much of a problem with Lemmy content being used for training because the data is open. When the our data is being sold around by big corporations, that’s shitty, but if everyone can use the data (which you posted publicly) to train models or perform analyses, I think that’s a good thing.
I can kind of see an argument that you exchange your attention for services online, but ads forced on you IRL should be illegal. If ads are a form of payment, then unsolicited ads are theft.