When I bought my CPDs a few months ago there were a few adult fish louse in the bag. Unfortunately there was one attached to a fish so I had to pull it off. That CPD died a week later...
Worst part was I bought them from a big named TPT member because I thought they were going to be nicer specimens than AB or LFS... when I PMd the seller they never responded. Luckily I had a spare 10g on my 40b rack that I used as a QT so I only lost a few plants. I treated them there and after a month or two of observation the CPDs made it to my main tank and there breeding like crazy now!
Inspect everything like it came from Afghanistan and is ticking lol, even if you trust the seller.