This is just some random thoughts i had over a hour or two so its a little unorganized
starting with champions, i feel like the new champions are made to look flashy and with no actual weakness in mind. It makes it really boring in lane and late game you end up with this fed champion with a overloaded kit that again has no weakness, or you end up with that same champion being completely useless because of there feast or famine play style.
There are also older champions who can abuse a keystone, they also lead to the same problem of feast or famine.
Alot of champions are well made but you rarely see them due to them having a play style that doesn't fit into the current meta, dont have a good item to build, and/or just being outclassed by a old champion that is abusing a keystone or a over loaded newer champion.
You end up having a 5v5 with 6 players doing a feast or famine champion but not everyone can feast meaning it ends up being a 3v7 for one team and those games arnt fun after a while.
If you look over your games you will see what im talking about, we keep seeing the same 10 champions over and over unless there banned. One team curve stomps the other team, the game is over in about 24 to 27 min.
Items on the other hand are ok ish, i wish there was less synergy between the items to open up alittle build diversity but i dont see a big problem there.
I do wish there where better starting items for melee champions into ranged and better armor and magic resist items to give more build diversity but again if nothing changed its fine where it is.
Balanced was thrown into wack with the keystones giving champions effects they where never meant to have at lv1, I dont blame them for doubling down on the keystone idea and making it do more in game but they do too much now. It seemed like a cool idea but people legit cant really play the game if they have the wrong set, That was not really a issue before.
that being said the main balanced issue is the team itself, there is a odd urge by the balance team to never hit the issues. A jg champion might be able to tower dive really well at lv3 due to there cc and movement speed but riot will hit there base magic resist or damage scaling on there ult, this method guts a champion instead of just solving the original problem. They also play favorites when it comes to champions, letting a champion go live knowing its too strong and leaving it for a month, but if a off meta pick pops up that counters that champion its nurfed within a week.
They also make useless patch notes that that could be summed up to " we redounded out some champion numbers", " this champion is getting a placebo buff", and /or " a skins coming up"
skins are whatever, they know where there cash cows are but there is no reason why a champion should only have 3 skins and there last skin was 3 or 4 years ago. they need to let there cash cows rest for a second and give alittle love to champions with almost no skins.
The last little note is the rng of dragons, they need some system where the dragon drops three orbs and the one who kills dragon can stand on one, you cant summon the same one twice in a row but you can choose one of the other three, It lets people plan teams around dragons to a degree.