I'm pretty sure that happened in [the week of December 12th, 2022](https://meta.stackexchange.com/q/383026/295232).

> Mobile has been shut down in its entirety as of December 12th, 2022.

I have a commit in the repository of my broken image repairer script dated December 19th, which replaces the [(mobile-app-exclusive) API call](https://meta.stackexchange.com/a/350381/295232) with something to simulate the upload via the website instead. I'm pretty sure I would only have done so because the API call did not work anymore. Deleted comments under the linked answer indicate it was still working on November 29th, 2022.