Just an FYI... I had updated my IPC-HDBW4231FP-E2-M a while back to the latest 241111 firmware from Andy's site. It works well, but recently I updated some LED bulbs to new ones and I realized that I was getting SEVERE camera flicker with one of the 2 cams pointed at them. I could get around it by using 1/120 manual shutter in the daytime but it's super washed out and that was the fastest shutter speed available in the 60Hz setting. Outdoor or 50Hz didn't have any other 1/60 speeds. I realized that Andy's firmware was the PAL version.
After some super digging around (why does Dahua make it hard to find firmware... what works one day won't work the next) I found the same 241111 firmware in NTSC, and now set to flicker=60 Hz and auto shutter, it's rock solid. I still only see as fast as 1/120 if doing it manually, but at least on auto it seems to go faster and still a multiple of 60.
Here's the link I used... it's the Dahua website and I just searched for "multi-rhea":
Dahua Technology is a world-leading video-centric AIoT solution and service provider. With its 'Dahua Think#' corporate strategy, Dahua Technology focuses on two core businesses: City and Enterprise.
www.dahuasecurity.com
In case that helps anyone else find it who might need the NTSC version for this reason.