And it'll happen again when AI models start resorting to ads once again.

Yup. Any LLM recommendation for a product or service should be viewed with suspicion (no different than web search results or asking a commission-based human their opinion). Sponsored placements. Affiliate links. Etc.

Or when asking an LLM for a comparison matrix or pros and cons between choices ... beware paid placements or sponsors. Bias could be a result of available training data (forgivable?) or due to paid prioritization (or de-prioritizing of competitors!)