From what I understand, this was never the case, and not even close. Toy Story took a ton of compute power to render (at the time), Soul took a ton of compute power to render (at the time).
They render them at a very high resolution, so perhaps the person I heard the rumors from was talking about reducing the resolution to something less than 10k by 10k (or more sometimes, I've been out of the film industry for 8 years).
I'm not sure there are feature films rendered at 10k. At least I can't think of a single studio or project that's that high for anything other than marketing or special projects
