Setting the trailer brake gain to stop both truck and trailer from 25mph in a reasonable distance with zero help from the truck brakes is setting them quite strong; too strong for stop/go traffic, in town with a bunch of stoplights, or anywhere with repetitive stops.
If you like the heavy trailer braking and want to maintain that for “normal” use, you’re going to have to turn it down when you get in stop/go traffic and turn it back up for “normal” use.
BTW, the OEM Tundra brake controller may be trash, IDK. I have a 2017 Tundra that came with a factory trailer brake controller. It isn’t a proportional controller. It’s an old style: set the gain and if you need more for a panic stop, use the manual slider. Maybe because that’s the type I’ve always used, I’ve had no problems with it on my old 9K lb camper, flatbed with loads from 2K (empty) to 9K lb, new 3500 lb camper. Works exactly the same as the add on A/M under the dash non-proportional brake controllers I’ve had on my prior trucks.
Stop/go type traffic, I do turn down the gain a bit and use the slider if I need to panic stop, as well as use the transmission to control speed in that sort of traffic to minimize brake use to necessary only. That’s because I’ve experienced trailer brake heating in stop/go traffic with all the various combinations of my trailers and trucks and brake controllers over the years if I didn’t do the above. Again, maybe you’ll get better performance out of a proportional control, don’t know, never operated one.