How do you think the OP is supposed to know that "SDDM" is the issue to look up? You don't get to enforce another person's effort. If all you want to provide is "you're looking for 'SDDM,' that would provide help and empower them without sounding like you're biting the newbie for not knowing everything.
Yes. I would assume that the problem is in X11 or Wayland before thinking it could be SDDM, frankly. But even then, googling "Linux login screen" doesn't immediately reveal SDDM to be the point of concern.
I'm not moving any goalposts at all. I'm expressing how inexperience and bad assumptions can make one's searching unfruitful through no fault of their own. That's all I've ever been saying.
Ah, you made an edit. Yeah, "kde login rotation" does, but "EndeavourOS login rotation" gives you no results mentioning SDDM. Giving people the benefit of the doubt costs you nothing over assuming that they're lazy, and the added bonus is that you don't sound like a jerk.