Why is this an issue?

There’s no reason to use literal boolean values in assertions. Doing so is at best confusing for maintainers, and at worst a bug.

Noncompliant code example

bool b = true;
NUnit.Framework.Assert.AreEqual(true, b);
Xunit.Assert.NotSame(true, b);
Microsoft.VisualStudio.TestTools.UnitTesting.Assert.AreEqual(true, b);
System.Diagnostics.Debug.Assert(true);