Looloosha,
I’m not speaking for A&H, but I think I can answer your question.
I own the SQ5, and I puchased the optional “SQ-BRACKET” that holds an IPad, or tablet. On the Sq5 there is only 2 mounting screws, but I looked at the SQ7 images and I noticed that they have 4 mounting locations, allowing for 1x “SQ-BRACKET” in the middle (See Images on SQ7 page) or 2 brackets side by side. I’m 99% confident that is what you noticed for the SQ7.
Judging from my experience the bracket feels solid when attached. It holds my huge IPad Pro easily. It also can be taken off (or reattached) easily without any tools while transporting the mixer between gigs.