Looks a bit different to the "glow on one side" that is usually shown. But as there is an amp on each pixel I would have expected a more overall "glow".
CMOS likely doesn't need 300 seconds and as you say it doesn't appear on shorter exposures, so use shorter exposures. We still seem to apply long long exposure CCD rules to a CMOS that is different technology. Change your thinking.
All the "Pro" versions did was reduce ampglow, then AP'ers upped the exposure times to reinstate amp glow. Then complained. Presently seem 2 ZWO's that say "No amp glow" and appear to deliver. However I have little doubt that someone will manage to still achieve some. Lets face it just leave it running for an hour or two and something will go wrong and I do expect someone to try.
Imaging course said that something like 2 min 40 sec CMOS was equivalent to around 10+ minutes CCD. Go for 150 sec, maybe 180 sec and just get more exposures.
Answer seems obvious: Change thinking from CCD technology, use CMOS technology to your advantage, make use of shorter exposures being adaquate, take shorter exposures and so avoid amp glow.
Look at stars under long exposure CMOS images, they are all "WHITE". No color at all, all blown out. That is too long an exposure. Color in stars tends to be one of the first things I look for/at. Most have none these days.