I will share two disasters where helping with math went wrong, so you can see what might happen.
In the first case I was teaching at a university, and part of the math faculty duties was to assist with the math tutoring lab one hour a week. The university had students to do most of the tutoring, while one or two of us was there to help with courses that the student tutors could not, like calculus and statistics. One student who often worked the same hours I did had just passed algebra, and gotten an A. So, he helped with algebra. But it was soon apparent he was doing severe damage. Hos approach, and often with objection from the students he helped, was to just toss everything the student had learned and insist on learning the method he understood. Faculty often have the skill to solve the problem by many methods. I would hear students pleading, saying that is not how we do it in class. But, he would not yield, possibly because he could not understand another method.
The other case was a high school student I was helping with physics. She seemed to know the material quite well. But her grades were in the failure range. One day, she had to divide one number by two others, like 90/(2X5). She typed the problem into her calculator and got the wrong answer. There was no use of the parentheses in her calculation, so she actually multiplied by the five instead of dividing by it. I explained the subtle difficulty and she started getting high grades. Then she told me that there were about ten others from her former elementary school, and all were having problems. Here, a teacher at the elementary school apparently taught the students to be calculator dependent, and failed to teach them the proper way of using that calculator. So, it was probably a teacher who caused damage by doing things wrong.