i can confirm, in my hs in a very blue cali area, tons of people were struggling the courses, and they just passed them for the most part. once they get into Community college, you can see a ton of them struggling in the most basic courses( of course students are from all over the us) but more or less they come from the same HS system(pass all D- high F grade earners). the professors themselves also notice this trend, at the time i was in CC, they said people were only getting a 9th grade math education, and a 10th grade reading writing essay education), it has gotten worst since then.

our CC also had university level stem courses, and you can imagine most dont do well in the class(C isnt really considered a good thing), in terms if you want to transfer to a UNIVERSITY(NOT A non-low level tiered one)