That doesn't explain why the 2018 polls were significantly more accurate, or why the polls were just as off if not moreso in deep red areas where Trump voters would in theory feel less pressure from the left. If polls are systematically biased for the reasons you say, we should be finding out because we look at the data and see that there is evidence of it, rather than just assuming that because there is an issue in society that it will affect polling in a specific way.

The data seems to support other theories, such as that Trump specifically got turnout from low propensity voters who are less likely to answer polls at all (rather than lying to pollsters like your theory requires). Or that COVID-19 and its uneven effect on the population meant that many more Biden voters were at home almost all the time to answer the phone while more Trump voters are less likely to be remote workers and more likely to ignore stay at home orders.