When a player has obtained an advancement and that advancement is revoked in the same tick, the client outputs

Told to remove advancement <ID> but I don't know what that is

followed by a

Loaded <amount> advancements

.
This is rather problematic for map makers, as advancements can detect things with much less strain on performance than commands; so the triggers are used to detect something and the advancement is then revoked. This effectively results in spam in the client logs making them massive in size.

Steps to reproduce:

1. Place an impulse command block with the collowing command:

   /advancement grant @p only minecraft:recipes/brewing/brewing_stand

2. Place a chain command block where the impulse command block is pointing to, set to always active and with the collowing command:

   /advancement revoke @p only minecraft:recipes/brewing/brewing_stand

3. Make sure you don't have the advancement first:

   /advancement revoke @p only minecraft:recipes/brewing/brewing_stand

4. Power the impulse command block, and check the client log.