The shandeh is that they force these poor people to tell their life stories, and make videos and post them online. It’s embarrassing people b’tzibur. It’s forbidden to embarrass a person even with the intention of doing them good, and like R’ Reisman, I have serious doubts about the reality of some of the ads, and exactly how much of the money actually goes to the people portrayed as in need.
And the idea of, “You’re guaranteed the segulah if you just give us the money,” is outright kefirah. HKBH makes the cheshbonos, not us human beings.