How to prevent outdoor landscape light water leaks?
I am not sure if allowed in Canada but in the US we are allowed and even required to provide a drain in things like this a small drilled hole that will allow the water to drain out should eliminate the pooling.  I used to have multiple drains on my big 1000w metal halide lights because they cool in the winter they suck the water in just like yours. A small 1/8-1/4” hole at the lowest point will help no matter how the water is getting in.