I agree. It's weird.
There are two elements to the story: 1. Biden pushed back on more aid. 2. Biden "lost his temper."
On the first one, that is a relatively objective statement. Whether it makes Biden bad depends on how you view the aid. Using the terms loosely, if you are a hawk, it makes Biden look bad and if you are a dove, it makes him look good.
On the second point, it's pretty anti-Biden. It's pretty rare that you would describe "losing your temper" as a favorable statement. "Biden passionately objected.." would certainly sound better.
And, another difference on it is it would be difficult to determine if "Biden lost his temper" from reading a transcript. It would imply direct observation, although it's possible a Republican leak would infer, reasonably or cynically, that Biden was angry.
So, with all that in mind...
....I think it's unlikely it's the House Dems. I could see them possibly leaking the pushback, but it's along different lines (money) than what their letter pushed. But the second part is straight up self defeating. There is benefit in dragging Biden down before an election. Public disagreement is one thing - demonstrating you are not just a party stooge. But anonymously hurting the brand before an election is silly.
...I think it's unlikely it's Meadows' branch. It is counter to their argument - that Biden is just a blank check.
...I think it's unlikely it was an intentional leak from Biden loyalists in the administration. Ok, it does undermine Meadows' argument about the blank check, but it builds the "Biden is an angry old man" image that fits tightly how Republicans try to paint him. If they leaked it, they did so incompetently. And they don't seem incompetent.
...it could just be a admin official - maybe someone on the military side - getting frustrated and going off script. There are more than just the two parties in Washington. The Trump White House leaked like a sieve. There is no reason to believe everything comes out of the Biden White House is intentional. But the fact the cited multiple people makes that less likely unless there are several hawks getting pissed. And it happened in June.
...Another strong possibility would be Republican hawks who inferred Biden was angry if the transcripts were shared with them. If Ukraine does ultimately prevail, it will be an accomplishment cited by Biden 2024 campaign, rightly or wrongly. The Republicans have an interest in painting it as Zelensky winning the war despite Biden, instead of because of him. And, of course, it helps with the angry old main image they are cultivating.