The bipartisan compromise, which featured concessions from both parties, included some wall funding in the hopes of generating GOP support. It was a relatively modest sum — $650 million, roughly 3% of what the Trump administration sought in 2018 — and the funding wasn’t even new. (As Team Harris reminded Axios, the provision “just extended the timeline to spend funds that had been appropriated during Trump’s last year as president.”)
Most of your points have nothing to do with this issue, but ok. Yeah she signed the bill, so did most Democrats, only to have Republicans back out of signing their own bill. One side is working with others and trying to accomplish something beneficial, the other side is crying about a border issue and then tanking any attempts to address it. None of that equates to the false narrative that Harris is flip-flopping on the issue.
This is still the strictly Republican bill that Biden was going to pass but was killed at the direction of Trump to his cult followers in Congress.
This bill may come to pass as is or may not when a bunch of Democrats get in who demand no wall... but this is the perfect carrot to dangle for disenfranchised Republicans at least up to voting day.
All political science research suggests moves like this are never a good idea. From the perspective of the campaign, they think they're "taking the issue away" but there's copious research about this specifically with immigration. What you're actually doing is telling voters the other side had better judgement on this issue and you've come around to their wiser view. This both signals to low information voters the other side has a better grasp of the issue than you and dispirits your own side. If you dig into the numbers, this move has never worked for anyone ever. This is typical of the DNC political expert class who are objectively bad at their jobs on a Poli Sci 101 level.
It spawns propaganda videos exactly like the one OP posted, stretching the link of "funding the border wall" to one minor aspect of extending the expiry of money Congress under Trump appropriated.
For better or for worse, to some extent Harris has a degree of separation from Biden, she's just playing the hand that Biden was dealt, and it's Democrats' prerogative to push back against that low-information narrative suggested.
Surprise surprise, the DNC is adopting the GOP's stances from 4 years ago as their official platform as the American Empire continues to get more and more right wing.