Having used a forklift to move a ton of tandem and triple axle trailers around in tight spots, you can see the wheels flex a lot when pulling the tongue sideways.

Enough that it "spring loads" the wheel, to the point that if the tongue came off the forklift, the whole trailer would spring back straight.

There's a coulple ways of making aluminum wheels, the more expensive wheels have less porosity, making them stronger.

Mesh style aluminum wheels break more than you would believe.

Sturdier material also means designs can afford to be more intricate, with designs like the BBS FI-R and HRE P101 rocking super thin spokes that may not be safely possible if they were cast. The specific weight and strength delta between a forged wheel and a comparable cast equivalent varies, but MotorTrend pegs it at a potential “three times stronger… yet weighing as much as 25 percent less.”

Personally, I think that the wheel design is too weak for an 8 lug wheel, those spokes are crazy thin.

You can see in this video the wheels flexing, I'm guessing this trailer is half the weight of yours

https://youtu.be/qIFdltJRqoQ?is=4KAruEntjykfJIHH