[MC-151475] Dummy scoreboard resets itself on its own

I created a datapack to give anyone without a dummy score of knowledgeBook of 1 a knowledge book and sets your score to 1. After a while of playing, a new book is given.

Two functions (in datapack)
tick.mcfunction (called by a tick function):

scoreboard players add @a knowledgeBook 0
execute as @a[scores={knowledgeBook=0}] at @s run function survival:give_knowledge_book

give_knowledge_book:

give @s minecraft:knowledge_book{Recipes:["survival:diamond_horse_armor","survival:enchanted_golden_apple","survival:golden_horse_armor","survival:iron_horse_armor","survival:leather_smelt","survival:leather_smoker","survival:saddle"]}
scoreboard players set @s knowledgeBook 1

There are no other commands resetting the score after the few hours I noticed it happening.