Like I said, I heard first hand from a US veteran who served there in Iraq and was with me in Ukraine. He said Iraq was "much worse" in terms of civilian casualties in his estimation. Almost all statistical estimates you can find online also seem to confirm this, the civilian death toll was much worse in Iraq.
The claim is definitely extraordinary since both wars are extensively documented, and we just know (like, we have verifiable videos) that Russia has much, much less regard for civilian casualties, employs much less precise fires, and Ukraine is more populous and dense than Iraq.
Besides, the numbers I could find are the other way around. This study [1] estimates 3,750 civilian deaths in Iraq, and this UN report [2] says 10,582 recorded civilian deaths (that is, it's definitely an undercount, unlike the estimation in Iraq).
[1]: https://www.comw.org/pda/0310rm8.html#3.3.%20Total%20Iraqi%2...
[2]: https://www.ohchr.org/sites/default/files/2024-02/two-year-u...