Dont' worry about it, you're relatively new to the game so you can easily adjust to new champions. This is what happens all the time, Riot perceive a champion as strong in competitive play (she has shit win rates in solo queue) then nerf it into oblivion because it's a mage. This is nothing new and has been going on for years.
There is strong reverse power creep in this game, every champion that existed at the time was significantly more powerful in past unless it was unviable at the time... which Syndra happens to be one of (win rates in the 30% range regularly at all Elos) but not due to raw numbers like other examples. Most her numbers were the same but she was even more glitched than she is now and had slightly shorter range on E and her passive did nothing for her ult. Yes just those small changes was the difference between her being powerful or useless.
It's pretty much tradition that if an AP champion is used mid in competitive play it will be nerfed unless its name is Fizz.