Aluminum along with other adjuvants and preservatives used in vaccines are likely a more substantial cause of autism than acetaminophen use during pregnancy. Note that vaccines given to children are also associated with acetaminophen use at the time of inflammation caused by these vaccines, so that could potentially increase the risk further.

When looking at populations that have lower rates of autism, I think of the Amish. And with the Amish you get less screen time, less exposure to artificial light spectrums, less exposure to nnEMF, less noise pollution less exposure to processed food (note that's been changing a lot over the prior several decades though). They are generally exposed to farming communities which creates a different microbiome. There have fewer medical intervention such as prenatal ultrasounds.

So I think trying to blame just acetaminophen or just vaccines is not sufficiently comprehensive.