This is an innovation and should be avoided. Writing the name of Allah is not something that was done by our Prophet salla allahu alaihi wa sallam or his companions! Repeating The names of Allah a specific number of times is also an innovation.

Just want to find out that someone just posted that her mom writes ya hafeezu. On a paper ,keeps it with her valuables so allah protects her stuff. Another man who had a near death experience said he is alive coz he had read ya hafeezu 11 times before touching the electric cables. I asked for an authentic reference she said its allahs name and there’s nothing wrong in reciting allahs name