Comment by TulliusCicero

> They said "opt in to training on prompts by default," which is coherent English and perfectly fine.

No, it's really not. It should read "opted in to training on prompts by default".

"Opt in" means "you have to affirmatively turn this thing on". "Opted in" means "the thing is currently enabled".

Which is why it's probably better to write it as "enabled by default". Much harder to misinterpret.