For the longest time, “liberal” seemed like it basically just meant “Democrat” the same way “conservative” has/had been used to mean “Republican.” Now, it seems like it means “bad Democrat” and is even worse than being MAGA the way many seem to use it. Where did its use as an insult within the [relative] political left come from, and what does it specifically accuse/identify someone of/as?
This is really just factually inaccurate though. Modern US liberals are actually further to the left than they were during the bush era, and are nowhere near as far right as the bush administration. (not sure about Reagan because that was before my time but I suspect it was similar). Democrats during that era were just coming off of the very centrist Clinton administration, and have gradually been moving left ever since.
The difference is the people criticizing liberals have become much more numerous and moved much further to the left than core democrats. Which is largely a good thing but I think it would help them be more strategic if they actually understood these things clearly.