The idea is that many people secretly vote for Trump but won’t admit or discuss it with others (including pollsters) because they are afraid of being harassed or attacked.

TL;DR anecdotal “evidence” incoming so take this for the grain of salt it’s worth:

I live on a light blue island in the middle of a deep red state. In 2016, there were almost zero Trump signs and his hardocre supporters seemed very much the random kooky outlier types. However, if you had conservative friends (of which I have many) and you were someone they didn’t fear judgement from, they would usually quietly say tell you they were voting for him over Clinton. To me at least, this seems to represent the classic “silent” Trump supporters.

Fast forward to now and -at least in my suburban/rural part of the world- it seems as if the tables are totally flipped; people who support Harris keep their political views more to themselves or their social media echospheres largely because they’re afraid of the (possibly violent) response they may elicit. At the same time, pro-Trump & anti-liberal bumper stickers, yard signs, and flags pepper T-shirts, vehicles, and front yards.

Is it different in large cities or other parts of the country? Do Trump supporters still tend to be more politically private? Or is that concept a thing of past?