Is this a bug?

i am having a problem with my league, i dont know how should i call this but sometimes in a game my champ is not listening to me, every movements is got delay, today i was playing zac and at the last minutes of the game i were in the jungle with my friend ekko then enemy jg and top show up i tried to run, i use my r i press it soo many times and it still not working, my champ just staying 1 place move a little bit then stand at 1 place again then after few seconds im still in the jg, at the crossroad leads from top to jg, my champ suddenly use r but i didnt press it ( i did press it before but its a few seconds ago ) but again the champ not moving keep bouncing at 1 place then move a bit at that moment i feel very panic so i press my flash button but it didnt work instantly, it only works a few seconds later. i meet this problem a few game before, not only flash and zac r got delay his e q and w too, also not only with zac i have the same problem with other champs too.