At this point, any request for information could potentially be used as training data. That includes things like captchas.
I recommend everyone have an extremely literal interpretation of "labor". Unless you have tremendous insight into where your data is going and how it is being used (and perhaps even then), then assume any ask is ultimately an ask for unpaid labor.
Obviously you can't avoid things like captchas, but you can avoid things like this.
Edit: and it should go without saying, but anything you upload to socials is probably automatic training data at this point. The best approach is simply not to engage with corporate social networks.
Though Lemmy is not corporately controlled, the information is publically accessible, so even this post is potential training data to be scraped. That is harder to avoid, lest we stop using the internet altogether, but at least avoiding the corpo routes is a good start.