Tags like rating:general and order:score shouldn't count towards the 2 tag limit.

I search for furina_(genshin_impact), I add order:score, I see porn. I add -sex, and I've gone beyond the 2 tag limit. WTF?

rating: does not count towards the limit. At the bottom of help:cheatsheet is a full list of the tags that don't count towards your limit.

furina_(genshin_impact) order:score is:sfw or furina_(genshin_impact) order:score rating:g

This should be a better catch for you unless you also want to see certain types of NSFW content (e.g. nudity) without it being outright sex acts which are in themselves not covered by just the sex tag.