There's really no way a leaky lid can fuel the coals.
There must be a draft coming from somewhere.
My UDS is a drum that's open on both ends.
I use the original cover as the bottom & don't even ratchet them together...There's a tight enough seal that I often have trouble getting them separated.
This seal gets better & better, with the drippings from each use.
My Weber lid also leaked, originally...
But, with use comes enough seasoning to seal that, as well.
If your coals are burning that hot, I suspect that something in the bottom of your UDS is feeding them oxygen.
22.5" OTS, 18.5" OTS, UDS, R2D2 & ECB