Why is this an issue?

Comparing a boolean literal to a variable or expression that evaluates to a boolean value is unnecessary and can make the code harder to read and understand. Therefore, boolean literals should be avoided in equality comparison expressions (==, ===, !=, and !==) to improve code readability and reduce unnecessary clutter.

This rule also reports on redundant boolean operations.

if (someValue === true) { /* ... */ } // Noncompliant: Redundant comparison
if (someBooleanValue !== true) { /* ... */ } // Noncompliant: Redundant comparison
if (booleanMethod() || false) { /* ... */ }  // Noncompliant: Redundant OR
doSomething(!false); // Noncompliant: Redundant negation

Remove redundant boolean literals to improve readability.

if (someValue) { /* ... */ }
if (!someBooleanValue) { /* ... */ }
if (booleanMethod()) { /* ... */ }
doSomething(true);

Resources

Documentation