The bug

Soul Speed, when used in survival, will allow damage on the boots to reach negative values without breaking the boots.

To reproduce

Run this command

/give @s netherite_boots{Enchantments:[{id:"soul_speed",lvl:3s}],Damage:480}

Then walk around on Soul Soil/Sand blocks for a few seconds and then check the durability of the boots. The damage will be negative. (Make sure to have Advanced Tooltips enabled, F3+H)