Deleted Files to Trash Bin

If a directory that is synced to multiple windows computers gets deleted, doesn’t the directory end up in the trashbin of each laptop?

Does the directory go to the windows trashbin at all or is there some trashbin inside the nextcloud sync directory?

No, there is a trashbin-app. If you delete a file, it goes into the trashbin of the user and the trashbin of the owner (in case it is a shared folder).
Using the trash bin of the OS was already discussed