Latency displayed as normal but intense lag occurred

Just played a game where I experienced 1-5 second delays on almost half my actions. Replay will clearly show me freezing multiple times at places I should not have. The effect was similar to 1000+ ping but the latency meter was reporting a consistent 53-54 all game long. I'm not sure if it was on my end or Riot's but according to my cohorts in discord I was not lagging at all through the course of the game, checking my internet speed after the game also confirms this.