Question:

Why do deleted Picklist values appear as options in Advanced Filters on Objects and Documents?

Answer:

Picklist values that are deleted still appear as options in Advanced Filters on Objects and Documents because deleting a Picklist value does not remove it from existing Documents or Object records. These values remain as Advanced Filter options since these values may still be populated on existing Documents and/or Object records.

Related Documentation:

Vault Filtering Documentation: Advanced Filter Mode