champion spells are lagging

my ping and connection are good, so my champions and nothing else is lagging or rubber banding but when i try to use champion abilities like flash or heal, they either flat out fail to activate or do so few seconds later from when i was pressing to activate them like they lag individually, and we all know how its like when you need your flash to activate in mere seconds or you are screwed cause enemy teams comes at you from all sides and you need over the wall to try and escape but when flash is failing to activate when you need it to the most you get stunned and chained cc until your wrecked, which makes you wonder whats the point of taking the ability if its not going to work for its intended purpose.