Just did a little research on your garlic “surprise”.
Apparently, garlic will react this way when there is significant copper sulfate in the cooking media or other ingredients. Perfectly safe, no worries, but, it does seem pretty weird,
As to finding pork loins? They are Common as fleas on a hound around here, try Giant Eagle. My sister lives in Pittsburgh and they run decent deals on them every few weeks. They go for $1.99/lb around here from one grocery store or another full ride, sale prices can run as low as $1.19!
A butcher may have a roast from heritage breeds which will doubtless be amazing but, will probably carry a pretty dear price tag. Maybe for a special occasion but, they are cheap enough around here that I can use them pretty much anytime I feel like boneless pork chops. I will get one and halve it, then slice the other half for nice chops, always cheaper than boneless chops in the 2 or 4 pack. I have three in my freezer almost all the time! Shop the sale.