Hi
It is possible that you have scratched through the fingerprint-resistant, oil repellent coating. It is normal for this coating to wear away under normal use, but it may have become scratched without damaging the screen beneath.
Unless the issue is due to a manufacturing defect, cosmetic damage - including scratches - is not covered under Apple's Limited Warranty (or AppleCare+). Your watch may be eligible for chargeable, out-of-warranty service.
I suggest that you contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider with a view to having your watch inspected and to establish any available service options, likely timescales and any cost:
I'm afraid that no-one here can tell you what Apple will decide. You are not talking to Apple here - this is a user-based technical support community.
Otherwise, a good quality screen protector (of the thin film type) may be effective in obscuring or reducing the visibility of the marks, as well as in providing some measure of protection against future damage. You may wish to consider, for example: