That's really cool Andy! I agree, the Philips versions of these bug lights produce lighter yellow light than the GE and Sylvania versions. Even my 2017 Polish-made Philips bug light has lighter yellow light like your 1990's Mexican-made one here. I guess Philips is good about sticking to the original recipe over the years.
I am thinking about comparing all three brands of my 60 watt bug lights and uploading some pictures of their light.