What you could try doing is to use versioning while also adding the .stversions folder to Syncthing without sharing it. Alternatively, you could use https://docs.syncthing.net/users/versioning.html#move-to-the-recycle-bin-using-powershell to send deleted (moved) files to the Recycle Bin while adding the Recycle Bin itself to Syncthing as well. However, there is still no guarantee that Syncthing is able to detect, scan and reuse blocks from the versioned files before it starts re-downloading them from other devices. I think some testing would be required to verify the actual behaviour.
Just for the record, this issue has been discussed in https://forum.syncthing.net/t/is-it-possible-for-syncthing-not-to-lock-files-in-windows-when-hashing-them/17086. In short, it’s by design by the Go language team, and the current and only solution is unfortunately to compile Syncthing yourself with a tweak described in the other topic. As the Go team doesn’t want to change the existing behaviour, a proper solution would need to be coded and implemented on the Syncthing side.