Search removes/ignores diacritics (e.g åäö)

I'm on CMS 11.10.5, Find 13.0.5.

Using For(query) in all fields or selected fields with no configuration overrides seems to match content regardless of diacritics in the query, e.g. "Miljo" matches content named "Miljö". However when using a specific filter such as Filter(x => x.Name.Matches(query)) the exact letters are matched (as expected/wanted). I've tried specifying the language, analyzer etc and I haven't found any information about special characters, diacritics, invariant strings in the documentation or source code. Is this behavior locked or can it be modified?

Edit: The actual indexed document shows the letters intact (åäö).