No hard data to back this up, but anecdotally I'd place the AI/copyright sentiment shift around mid-late 2022. DALL-E 2 experimentation (e.g: [0]) in early-mid 2022 seemed to just about sneak by unaffected, receiving similar positive/curious reception to previous trends (TalkToTransformer, ArtBreeder, GPT-3/AI Dungeon, etc.), but then Stable Diffusion bore the full brunt of "machine learning is theft" arguments.

[0]: https://x.com/xkcd/status/1552279517477183488