Fair question. Whether or not some age groups are more susceptible to propaganda is an empirical question. If you know of data, please share.

Critical thinking keeps developing into the early 20s, so not have the full supply of that is a potential knock against younger voters.

Something I’ve seen from my more conservatively-oriented family members is that significant financial and domestic difficulties help them see the falsehoods in right-wing propaganda. When things are better, they might be more amenable to anti-immigrant talk (and the like) to prop up their ego. But when they’re truly struggling (with affordability issues) they seem to see the irrelevance between their real issues and the parties the Right tries to scapegoat (e.g., immigrants; not billionaires, neoliberalism, etc.). If this theory holds, then not facing affordability issues due to living with parents could be another knock against young voters if it makes them more susceptible to right-wing propaganda.

Those are just speculations. I’d love to see some data!