The worst thing about complaint threads is that they get more attention and feedback from a community than question or strategy threads. Hence why they exist and will keep existing. Giving attention to a social problem such as this only feeds it.
"Well there's your problem."
Sketchy behavior has been happening on the game in the form of oddly overpowered individuals and questionable connectivity status. Games that do not have a huge financial backing in a security server construct tend to suffer the old tricks. Lag switching, bridging, etc etc. I've only noticed it when playing with tops on the leaderboards or league sensitive quick matches. Shady stuff at the top. But also, those tops have poured a TON of money into Happy Cards to try and get the best of the best. So some of those kills are from a $100+ investment to have an uber gear smite you down, or a sketchy game manipulation that they justify as "protecting their investment."
If you ever need to take a break from others cheating or using cash to smack you down, just play Coop Mode. The AI will never lag switch you.