I think the best evidence of where polling truly lies is the behavior of the Harris campaign:
Ask yourself first - who has the most resources and the most motivation to have super accurate information on who is winning, and who specifically (demos) is voting for Harris, and who is voting for Trump?
Answer: Harris campaign has $1 billion in campaign cash, and truly understanding what is going on across different groups regardless of spin / public perception is the key to running an effective campaign and targeting those groups that maybe are slipping, but you need them to win.
Now ask yourself - who has done a total 180 in terms of their campaign strategy in the last week or so?
Bear in mind that their clear strategy since she was announced was to rely on "joy" and vibe", "Brat summer," and above all else, avoid speaking to the media about anything at all.
Now:
-Harris doing interviews and talking to everyone all the sudden (but saying nothing).
-Obama is getting on a soap box with maximum moral superiority, condescendingly guilting black males who would dare vote for Trump that they are betraying their own.
-Multiple articles from left leaning sources all the sudden hitting the panic button, with what was 100% positive / glowing coverage of Harris skewing to allow for at least a few articles that point to what she is doing wrong and panic amongst her squad.
-Even after winning the first debate, she is trying to goad Trump into a second one, even signaling she might consider doing one on Fox news.
-Doing a CNN town hall
Meanwhile Trump is doing what he has always done, but you see a comfort level he hasn't shown since the period of time between the Biden debate and Biden getting coup'd. In short, he feels like he's playing with a lead, and he generally shows much better when he feels that way relative to feeling like he is on his heels.
If the Harris internal polling was re-assuring to Harris people, she would literally be in a bubble right now with duct tape over her mouth. I personally hope they do that to Trump and let Vance be his voice from now on. Had he done that after his ear getting snipe'd, we wouldn't even be debating polls right now.