You have a server Nextloud and the PC on which is stored a photo. Periodically, the PC starts a full sync, all folders are cleared and starts pumping with stupid servers which takes a lot of time.
It should be noted, files after synchronization all over the place. In logs no errors, just the info that is synchronizing with your PC.
The only thing that comes to my mind - system (Win10) and the client Nextloud installed on the SSD and photos are stored on an ordinary HDD (Hitachi 2 TB) and at the time of starting the system some time does not see the HDD. Sometimes out BSOD with different reasons.
Have someone any idea or has encountered similar ?