Don't understand the point of this HN post. This has been the case since at least 2008. See: https://web.archive.org/web/20081001000000*/gmail.com
3,393 karma · joined November 9, 2019
In my case even plaintext, because subdomain B has no HTTPS.
Losing important photos and memories is something that must not happen. The worst thing is: The user may not notice the problem.
* In my case 15 of 23 photos were uploaded (In other words, I would have to count the photos after uploading them)
* Nextcloud does not report an error to the user
I was lucky that my smartphone has a trash bin and I even noticed the problem.