False positive Open declaration can be removed when using extension for builder

[BoundedChenn31]

Here is the half-done maybe CE
Repro steps

Here is the half-done maybe CE, extension for it that adds Bind-overload and usage attempt:

namespace Case1

module MaybeBuilder =
    
    type MaybeBuilder() =
        member inline _.Bind(optionValue: 'T option, f) =
            match optionValue with
            | None -> None
            | Some value -> f value

        member inline _.Return maybeNull =
           if isNull maybeNull then None else Some maybeNull

        member inline _.Delay f = f

        member inline _.Run f = f()

    let maybe = MaybeBuilder()


module MaybeBuilderExtension =
    
    open MaybeBuilder
    
    type MaybeBuilder with
        member inline _.Bind(maybeNull: 'T, f) =
            if isNull maybeNull then None else f maybeNull


module Usage =
    open MaybeBuilder
    open MaybeBuilderExtension // TODO: false positive

    let foo (s: string) =
        maybe {
            let! a = s
            return a
        }

Visual Studio marks open MaybeBuilderExtension as safe to remove.

However it would break compilation of code because we actually use Bind from extension.

Expected behavior

open for builder extension isn't marked as unnecessary.

Actual behavior

It's marked as unnecessary.

Known workarounds
.

Related information

.NET SDK: 7.0.403
Visual Studio 17.7.6