"Cloud Sync Conflict" with different save times
Symptom
The Cloud Sync Conflict dialog shows different cloud and local save times. Picking the wrong one rolls your progress back.
Before you choose, copy
%appdata%\EldenRing\<your Steam ID>to a safe folder.Compare the times in the dialog with your last play session.
Choose the most recently modified (newer) save. Then let Steam upload it and download it to the PC.
If it keeps happening, turn off Steam Cloud for Elden Ring and back up by hand.
Unverified: In 2022 Bandai Namco confirmed a bug that could stop saves uploading to Steam Cloud. Whether it is fully fixed today isn't known.