Part of the problem is that polling has been fundamentally flawed for a while now. Polling in 2016, 2020, and 2024 all showed Trump as losing and the polling agencies had to artificially weigh pro Trump supporters higher in the polls because they weren't being adequately represented. It seems that a major portion of the problem is that some number of liberal/socialist poll respondents don't end up actually voting and some number of conservative voters don't end up responding to polls.