Not A Bug Bug Report - Random Battles

[shiba]

What type of bug are you reporting? Random Battles

What is the bug?
TLDR: Speed Bug.

Basically, i had sticky web up and a was speed debuffed. According to the stats, its max speed was only 159 before the debuff. I used flash cannon on my heatran which had 169 base speed. According to this I should always outspeed no? did my sticky web bug out and somehow let him outspeed me? His item was also not scarf, it was sitrus berry and he used drain punch, a non priority move so i dont understand.

Match Link:
https://replay.pokemonshowdown.com/gen7randombattle-2045308461-dmkij728jgz2j93nyysnb6esu5lt758pw

TURN 18

Are you able to replicate it? If so, how?
Idk how it even works

 

[Chains of Markov]

Slurpuff has the ability Unburden:

If this Pokemon loses its held item for any reason, its Speed is doubled as long as it remains active, has this Ability, and is not holding an item.