Up until about a week ago, and arguably up until the present day, she basically can't have a platform that's any different from Biden's. If the president says one thing, the VP's not gonna come out and say "actually he's wrong, we should be doing this other thing."
Now that she's the nominee, I expect that she'll have a platform relatively soon, although it's still a tricky thing; if her platform is to rein in Israel and Biden's is to keep giving weapons and asking them politely to stop killing, that could create some issues. I'm sure they'll work it out though and she will have a platform. It's not some scandal, and as soon as the platform appears, the freakout and attempt to criticize her will switch to some other invented scandal.
Still trying to push the Democrats to the left, hm? Yes yes this certainly seems like a sensible part of that effort and guaranteed to produce that result, and not at all an attempt to just suppress the Democratic vote from the left for totally weird reasons, or anything.