Why are people infantilizing people in their early 20s suddenly?

Its crazy as I am 24 and prefer women within 20-30 age range and sometimes seeing these people online make me worry whether 20 as minimum is even reasonable for someone my age. I am finishing my MBA now and an intern so I do meet women in their early and mid 20s all the time. In my internship there is a woman who is 20 and an intern similar to me and we are in the same life stage but I worry whether its weird to get to know her as people are weird about even small gaps nowadays between even adults in their 20s but I don't even feel the 4 year gap between us at all like when I was 22 I definitely felt a bit of a gap compared to 18 year olds but at 20 and 24 the gap feels smaller. Before only 18 and 19 year olds were infantilized(yeah 18 feels too young for me now) but now I am noticing even gaps like 20 and 24, 21 and 25 and 22 and 27 or even 23 and 28/29 are getting judged. These makes me feel whether going for a 20 or 21 year old woman is fine at 24 or not. Many women I know are within 20-26 (majority are 21-25 tho) range. With foreign women(mix of expats and tourists) in UB City I talked with multiple western and east Asian women in their 20s and 30s and one Hungarian woman who was a tourist was literally 40-45 but she still spoke warmly to me. So idk why this infantilizing. What do you feel? Is 20-30 age range preference reasonable at 24?