The proper DMX512 connector is XLR, though? The 5-pin variant, that is.

I worked as a tech at a stage for a short while. We always used XLR5 for lighting and XLR3 for audio.

Yes, I only saw 3-pin XLR for DMX512, while being aware of 5-pin XLR as "correct". Everything from the lighting console, to dimmer packs and moving heads, to the aforementioned connection to house lights. This was 2009-2013. Maybe it was regional?