Given this UnitRwsr1.fs in a Xunit V3 F# project:

module Demo.UnitTest1

open Xunit

[<Fact>]
let ``This.is.a.valid.name.in.F#`` () =
    Assert.True(true)

Then see this in Visual Studio's (2022 17.12.0.Preview 1.0);

where it is clear the periods in the function name have been parsed as part of the namespace and module. (Without periods in the function name Test Explorer displays correctly.)

(It is not clear to me where the unit test runner to VS integration point is, so I will understand if this is a VS issue...)