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