True, yes. Totally agree with you on the fundamental definition of opt-in vs opt-out.

You can also have a checkbox that says "I consent to having my data used for training", which would look like "opting in", and it could be true by default.

Or you can have a checkbox that says "Leave my data out of your training set", which would look like "opting out", and which could be unchecked default.

Technically, they're both "opt-out", but I've seen enough examples (intentionally confusing and arguably "dark patterns") that I personally don't really consider "it's opt-in" to be a complete statement anymore.

Edit: I'll add that, in the comment I was replying to, it very much looked like you had to go to a settings page in order to opt-out, which I think is entirely reasonably described as having been opted-in by default. Here's what they had written:

> All you have to do is flip a single switch in the options to turn it off

And I actually think "opted-in by default" is valid and calls out cases where it looks like you consent, but that decision was made for you. Although in this case I think I've seen other comments that describe the UX differently, but my comment was more of a general comment than about this particular flow.