What if you set to lower resolution and max bitrate does it improve day time video? Since it's newegg you could easily return it and btw if you didn't get Huisun cam you will be much happier with the results even though it's not 4k.
Lowering resolution also lowers the max bit rate. Good grief! I just tried (at night) 720p @ 10 FPS @ 2.8 Mbps and 1080p @ 10 FPS @ 5 Mbps, and both look significantly worse than 2160p @ 10 FPS @ 9 Mbps.
I'm keeping this cam, though mainly as a toy to look at the scenery. I am going to point it up a bit further so I get the hill tops and some sky, and hopefully not have a dynamic range problem.
Regarding Huisun... Yeah I've tried them. My dad wanted some cheap PTZs last year so I had him get two Huisun V1 bullets. By some miracle, they both still work, although one of them was unresponsive from December to July at a remote site where we couldn't get to it and power cycle it. The only camera brands that have not disappointed me yet are Hikvision and Dahua, because despite their flaws they are just so much more reliable.