*Update*
Went to talk to a service rep and showed him the photo. He was not at all surprised when he saw it and said that this is sealant they use due to the high number of weeping drain plugs they have experienced. Sounds like they have had a lot of similar complaints from people including a few who tried to get oil changes elsewhere and were turned away once the techs at the other shops saw the oil pan. I was assured this will come right off when I start turning the plug and is not what it looks like. Looking around at a few references to seeping plugs, some on this forum, seems plausible. As for the different plug he stated they often swap the original with a hex head equivalent. I do see this is a legit genuine Mazda part:
https://www.mazdaparts.org/mazda-oil-pan-plug-washer.html and I've read a few discussions where people recommend swapping to the hex head version.
So long story short, their explanation seems to add up and my BS meter didn't go off talking to the guy so as long as the drain plug comes out without having to wrench on it like crazy and the pan and plug threads look ok, I think I'm good.
Ran this by two people I know, one who used to run his own shop, and they were both convinced it was a stripped oil pan as well when they first saw it, so this must be a pretty uncommon thing to do.