The first two tests involving "" and "aa" are failing. Please have this corrected.
The description says if the length is less than 3 return false. Comments below
shows that this has been an issue for a longtime. Correct this

The description stated length less than 3 should return false, but this is not implemented. Non letters should not be considered

There should random tests including tests that check for _ and numbers.

Why is less than three characters a problem for palindrome checking? Why does the model solution not check this?
Also, nice to have random cases.

python tests are wrong, both test cases and sample tests:

• don't use test.expect
• assert_equals will do the them without inconsistencies between the message and the expected value (see sample tests)
• in the message, display the input string too. Without it, the message is useless
• no random tests
• example tests are lacking in the test cases
• The function should also return false if the string has a length of less than 3 letters or fewer than 3 alphabetical characters. => this behavior isn't tested in the test cases and moreover, in the sample tests where they are tested, the wrong answer is expected!

The function should also return false if the string has a length of less than 3 letters or fewer than 3 alphabetical characters.

Sample test error message for 'bob' is wrong, it's testing for true instead of for false.

The sample test for test "aa" and "bob" expect false when they are in fact plaindromes.

are you trying to eliminate a recursive solution?

and it is! ;)

I know, but it seemed strange to me.

The function should also return false if the string has a length of less than 3 letters or fewer than 3 alphabetical characters.

=> because you're beeing asked for that particular behavior (even if...) ;)

Why "aa" shouldn't be considered a palindrome?

It's similar to many others and a duplicate too, you will find a list at: https://www.codewars.com/kata/search/?q=palindrom