The Bug:

The word "block" in the "Wax on" and "Wax off" advancement descriptions is improperly capitalized.

Steps to Reproduce:

• Grant yourself the "Wax On" and "Wax Off" advancements.

/advancement grant @s only minecraft:husbandry/wax_on
/advancement grant @s only minecraft:husbandry/wax_off

• →  Notice how the word "block" in both advancement descriptions is not capitalized.