The past red trust, the change of merit awarding behaviour shortly after new restrictions and the timing of merit awarding with 20 sec intervals is enough factors for me to think that it is farming after all.
Please let's not use timing as a criterion for abuse. I often open a bunch of +Merit in tabs and then just submit them all and I'm sure I'm not alone doing that.
I'd also caution (and this is not specifically directed at you mazda) against getting too carried away with some of these abuse allegations. I've always maintained that
merely sending and receiving merits is not a proof of wrongdoing. Of course if there is any other malfeasance involved (provable alts, quid pro quo, etc) then it's different. But some of these recent allegations seem to be based entirely on someone sending 1 merit to multiple users. Let them have it. If they're shitposters they'll get banned and will eventually run out of merits. Let's hit them where it hurts and report those spam posts.