I can't understand the outrage here. We received five cautions. UEFA rules state that teams receiving five cautions in a single game will be sanctioned. They are just following the rules, as they do with every other team.
You might argue that some of the cautions were soft, but that's down to the referee, not UEFA.
You might say it's unfair that four cautions and a dismissal is worse than five cautions, but the player sent off will receive a fine and a ban, which is arguably a more severe punishment than ours. You could argue that this deserves a club punishment as well, but that would require a rule change I presume.
Blame either our players for their poor discipline, or the referee for being biased against us, not UEFA on this occasion.