Commenting because I went through this maddening and incomprehensible process last year and got rejected a bunch as well. The thing that I believe worked for me

Commenting because I went through this maddening and incomprehensible process last year and got rejected a bunch as well. The thing that I believe worked for me was that I completed domain verification via my business manager account (which was also a journey in and of itself). Once that came through, my Tech Provider application was approved within the next day or two.