ZL1 Brick?

I have a reinforced ZL1 brick. I have a 8 gallon ice tank located in the trunk. I have noticed lately that my water level is going low but I’m seeing no leaks at all, anywhere. I ran distilled water all summer, no issues. I just drained a lot of it out and did the usual 50/50 mix for winter time about a month ago. Made sure it was primed, filled and burped. In the past 2 weeks, it has gone so low it turns my pump off when driving and I see my IAT2 go up to about 108 when cruising (that’s typically how I know it turned off)

I took the lid off and I see zero signs of it leaking from the brick. Turned pumps on and it’s sealed tight. Bone dry in the supercharger. I have absolutely no leaks under the vehicle… I filled the lid up with the brick and pressurized it at 25psi and no air leaks.

Am I missing something? I do not beat on this car… I just cruise around, maybe occasionally a hard pull here and there but nothing crazy. In the past week I have put 4 gallons of distilled water in the tank, it has gone down that low. It runs cool all the time (+\-10 ambient). Cruising at 70mph, on a 70 degree day I’ll see it sit at 70-80 degrees roughly.

I’m at a loss. Maybe I thought I added enough 50/50 mix? Maybe the brick only leaks under boost? I never see boost hardly at all…