As something that could be introduced in Syncthing v2, I would like to suggest improving ignore patterns handling on Windows by changing how \ is treated. This is a breaking change, but basically, \ would be used as an escape character (as is the case in other operating systems), and if one wanted to use it as a path separator, they would need to escape it as \\. Using double \\ isn’t new in the Windows world, as path separators already need to be escaped like that, e.g. in the Registry.
This change would allow Windows users to escape other characters in ignore patterns, like { or [, which isn’t possible right now, as \ is treated literally.