What kIind of logical fallacy is this?

In a Debate A is starting to lose against B.Even A knows that.But A doesn't want to lose so he started to give advise to B.
A is a rich person who caught B poor person when B was trying to steal some foods.But B was able to showing him that what he done was indeed a sin But rich persons are more sinner than B.As they don't help poor persons so they have no choice but stealing. B was winning the argument But A trickily started to give advise to B instead of Debating.

What kind of logical fallacy A has done?

Looks like a red herring. See https://www.logicallyfallacious.com/tools/lp/Bo/LogicalFallacies/150/Red-Herring<>.

It's a challenge to make sense of this from the clumsy narrative, but I'd say B's
argument is a classic Tu Quoque (You too - whataboutism). See Dr. Bo's:

Ad Hominem (Tu quoque)
argumentum ad hominem tu quoque

(also known as: “you too” fallacy, hypocrisy, personal inconsistency)

Description: Claiming the argument is flawed by pointing out that the one making the argument is not acting consistently with the claims of the argument.

Logical Form:

Person 1 is claiming that Y is true, but person 1 is acting as if Y is not true.
Therefore, Y must not be true.
Example #1:

Helga: You should not be eating that... it has been scientifically proven that eating fat burgers are no good for your health.
Hugh: You eat fat burgers all the time so that can’t be true.
Explanation: It doesn’t matter (to the truth claim of the argument at least) if Helga follows her own advice or not. While it might appear that the reason she does not follow her own advice is that she doesn’t believe it’s true, it could also be that those fat burgers are just too damn irresistible.

Example #2:

Jimmy Swaggart argued strongly against sexual immorality, yet he has had several affairs with prostitutes; therefore, sexual immorality is acceptable.
Explanation: The fact Jimmy Swaggart likes to play a round of bedroom golf with some local entrepreneurial ladies, is not evidence for sexual immorality in general, only that he is sexually immoral.

Exception: If Jimbo insisted that his actions were in line with sexual morality, then it would be a very germane part of the argument.

I agree w/ all the other answers.

However, let's add Two Wrong's Make a Right. Just b/c A is bad doesn't mean that B is good. Just b/c B is bad doesn't mean that A is good. Two wrongs don't make a right; they just make two wrongs.

Sounds like an ugly debate, doesn't it?

We cannot know if A is in error or guilty of a fallacy without knowing how specifically he is responding to B's Ad hominem Tu quoque argument. All we are told is that he is "advising" B and not debating him. If A is deceptively shifting away from the argument, or, keeps changing the subject, then, yes, it would be a Red Herring, or, possibly another type of fallacy.

If A is advising or informing B that his argument is a logical fallacy, and that his own thievery cannot be justified by blaming it on the hypocrisy of the rich, then, that would be a proper debate response. (At least, according to Analytics, one has the responsibility to call out a fallacy when first confronted with one).