My understanding is the booking class makes all the difference in earning PQP.
For instance, booking in economy (T) earns only 50% of milage on preferred partners. Premium economy (Y) earns 150% and (N) earns 100%.

As to "correct what," that question only needs to be asked if in fact the class on BRU-ORD has changed. I'm not seeing anything currently on their website, only the 'Business' classification in the image on my OP. Looking at United's site, they have it as PZ (makes sense).
My concern is the 'cancellation' of the Premium Economy booking and LH rebooking it under Business, but possibly under an award redemption since UA has it as PZ. Since PQPs are not earned on awards, does the PZ upgrade eliminate the BRU-ORD PQPs?