It's pure bedlam right now, I'll try breaking it down the best I can.
1.) They made some pretty hefty changes to Items/Champions over the last few months that completely changed everything around. Mage Changes were made to make Itemization less linear, but alot of people say that the Mages were pretty much nerfed completely after this & the Mana Regen changes. Jungle Changes were done to kill Early game Pressure & promote early invades, but this more over made it so 5 Junglers are the only ones being played. AD Itemization Changes were done to make ADC builds less Linear like the Mage Changes & to "Open up Botlane", Crit Based ADC's were weakened severely in their Early game & in some cases are being outclassed by Mages & even Bruisers/Skirmishers.
2.) Aatrox
, Swain
& Irelia
have been completely overhauled. Aatrox went from being a Auto-Attack based Diver to a Juggernaut/Diver Hybrid (Diver once he hits 6 thanks to his revive), He feels like a completely new champion that retained almost nothing from his previous incarnation. Swain is still a Battle Mage & is still pretty cool in my opinion, he was hated at first but I think people have come to accept him as he is now. Irelia feels a bit more fleshed out compared to her previous incarnation & is quite strong in the right hands.
3.) Zoe
, Kai'Sa
&
are completely new to the game. Zoe is a Burst Mage that 95% of the community hates because of how her kit works, she used to oneshot people with Dorans ring on release. Kai'Sa is a ADC that can be played AD or AP, she's quite notorious at the moment for some reason (I actually don't know why she's being hated). Pyke is a Assassin-Support that I haven't seen many complaints on so far, I think he's in a good place at the moment.
4.) Not so sure about the Client Issues or 12 minute queues, but think the VERSUS event might have something to do with it (I could eb wrong about this). Alot of people love URF (ARURF will never live up to it's expectations, but will do..) & Event-Only loot is something alot of people are trying to get their hands on before Versus ends July 10th.
5.) There's alot of Toxicity mainly because of people's frustration with the direction League is going & they're taking it out on their fellow players. There's also the Matchmaking being busted & putting players into matches where they have little chance of winning, that's another issue that's being prevalent. You also have other players that just act up just for the Lolz. Not much you can do about that besides reporting them after the game is over, unfortunately some players would rather verbally retaliate instead (which leads to them being punished by the IFS with a Chat restriction/Permaban)
Think I hit all the points, might have left a few out & some of this might be inaccurate. Also, I'm sorry about the wall of text.