but it was all but confirmed for me when I noticed both you and QS reporting posts with the exact same phrasing. The odds of that happening between two random people is very rare and obviously not something someone else can mimic.
That can give false positive result, someone ask you for advice and you say "report it to moderator, write this in comments: (insert comment)". So they just c/p that and report post or use very very similar words. It is nothing unusual I guess. How many similarities are you talking about, if it is not secret?
Everything here and in other thread is circumstantial evidence, there is no rock solid proof of connection, even PrimeNumber7 attacking only suchmoon (as o_e_l_e_o pointed) is circumstantial evidence. Having that said, there is probably nothing which will convince me that PM7 and QS are not alt accounts.