IDE0044 "Make field readonly" false positive when used in ref return

[Tragetaschen]

Version Used:
16.0.0 Preview 2.0

Steps to Reproduce:

public class C
{
    private int a, b; // IDE0044
    private ref int select(bool c) => ref (c ? ref a : ref b);
    public void Test() => select(true) = 3;
}

Expected Behavior:
The members are mutated. Marking them readonly breaks the code, so IDE0044 shouldn't trigger.

Actual Behavior:
IDE0044 is falsely triggered.

[kindermannhubert]

Same here:

class C
{
    private int x; // IDE0044

    public void Foo()
    {
        ref var xRef = ref x;
        xRef = 7;
    }
}