Polling data has been way off since 2016, and seems to be getting exponentially less reliable with every subsequent election cycle. First off, lots of these polls are collected by cold calling landline telephones, which today doesn't exactly paint an accurate picture of the electorate considering the demographics of people who will actually answer a landlines telephone call from an unknown number.
Second, have you not paid attention to any of the special elections that have taken place around the country in the last few years? If so, considering the Dems have overperformed by an average of 11-points over the last 30 special elections. I don't even see how someone can be vaguely aware of politics and believe there is any positive momentum coming out the Republican party that would in anyway sway independents/moderate/anyone who isn't already knee deep in right-wing propaganda kool-aid -- Roe V Wade has effectively ruined the current iteration of the Republican party, especially at a national level. The media is perpetuating this false narrative that the election is in a "dead heat", the exact same way they did in 2020. Why? Because blowout elections aren't sexy and don't generate engagement.
Like, even just applying some basic armchair logic: If Donald Trump lost by almost 8 million votes, as a sitting president, before the 91 criminal convictions, and before Jan 6th, and before his progressively more deranged outbursts on Twitter, in what world do all those aforementioned things, in a political climate in which Republicans have been getting dominated in almost every statewide election outside of Florida, seem more politically viable to moderates and independents?
The mainstream media is perpetuating a false narrative of the closeness of the election, not necessarily because they want Trump to win, but because, Trump being in headlined, whether you like him or not, is a license to print money for the large media companies. Also, current polling data has a hard time quantifying the effect of negative partisanship, and seems predicated on the false dichotomy that because people aren't thrilled about Biden (he wasn’t my 1st, 2nd, or 3rd choice, but I've been pleasantly surprised) that somehow must mean they support Trump.