That is definitely a cast iron griddle pan

I agree though, you gotta get that thing hot and sear to increase flavour and texture.

I suspect the real problem is too many burgers at once.

If you keep the heat constant and add a patty it will quickly absorb the heat, the griddle will cool down, and the patty will either stay above sear temp or drop below it. If it drops too low it won’t fully sear, and the fat will boil instead of evaporate, causing the burgers to steam.

For 1-4 patties I think this works out on this pan, you can find a good balance they stay above sear the whole time while they cook through. But for 8 patties you get that catastrophic cooling. The patties and fat absorb too much heat, the fat boils and doesn’t steam off, then the patties go grey.

The heat needed doesn’t increase linearly: going from 4 to 8 burgers requires more than twice the heat input.

If you’re grilling on a bbq this is less of an issue, because heat doesn’t spread across a oan surface in a significant way, and the fat doesn’t pool. So you can load up a bbq without issue.