This is where the guidance gets far less concrete, and where we have to rely on our experts to make decisions. What we are looking for here is some combination of terminology, concepts, and mechanics that, when considered together, uniquely identify one system. Unfortunately, there is not really much concrete guidance here. As always, the more details we have, the more sure we can be. Ideally, we would have multiple system specific game terms, such as the name of a feature, spell, or mechanic, butbearing in mind that such names are often reused from edition to edition. However, sometimes a system expert will be able to correctly identify the system with a single piece of identifying information.
I've added the [dnd-5e] tag since you mentioned bonus actions, Tasha's otherworldy disguiseguise, and Wild Magic Sorcerers. Could you confirm this is correct?