Right click champ completely glitches out

So I switched to an alt account to play with a lower lvl friend, and in-game every time I would right click to move my champ, which is constantly, the champ would literally glitch out and the best description I can give is like a particle...popping in and out of existence, reappearing instantly in another spot nearby. The champ is clearly moving where it should be behind the scenes, but visually, it's completely off-putting and unplayable, my brain can't decide where the hell my champ is at any given time, and it is impossible to suffer through an entire match...

I found a thread for this exact same thing from 3 years ago, and saw only two replies, none from Riot. Is there a fix for this? Why is this happening? Finally, what in the world...