Invalid type constraint compiles successfully when specifying type intersection

[DedSec256]

This code is meant to be invalid, since additional restrictions of the form :> SomeType should not be used in type intersection:

let f (x: 't when 't :> ABRAKADABRAA & #seq<int>) = ()

However, it compiles successfully, and you can use any not existing type name instead of ABRAKADABRA.
After decompilation, the false constraint is not present in the final build.

As you can see from the white identifier and unused open, the compiler doesn't even return a symbol for an existing type.

Reproducible in the main branch via test:

[<Fact>]
let test () =
    Fsx """
let f (x: 't when 't :> ABRAKADABRAA & #seq<int>) = ()
"""
    |> withLangVersion80
    |> typecheck
    |> shouldSucceed

.NET 8.0.100