When Opera is closed or restarts, the pinned tabs pinned to a specific Workspace (2+) are all moved to Workspace 1.
To give a scenario:
If I have Google.com pinned in Workspace 2, Apple.com pinned in Workspace 3, and YouTube.com pinned in Workspace 4, then Opera shuts/restarts/updates, all of these will be pinned in Workspace 1.
This was caused by the newest update and very inconvenient.