Impossible to satisfy R#

I have a class which implements IFormattable. No matter what I do, R# complains about the provider parameter.

Starting with:

public string ToString(string format, IFormatProvider formatProvider = null)

R# complains that I need to add [CanBeNull] to the parameter:

If I accept that suggestion, I get:

public string ToString(string format, [CanBeNull] IFormatProvider formatProvider = null)

and R# now complains that the base declaration has the same annotation:

I'm also seeing the same problem with implementing IValidatableObject - R# wants me to annotate the Validate method with [ItemCanBeNull], then complains that the base declaration has the same annotation.

And the same problem implementing a Newtonsoft JsonConverter that I reported two years ago, which is still "triaged" and not fixed.

R# 2023.1
VS2022 v17.5.3