As given in the docs when sending the query string like
http://localhost:3100/Customers?join=facilities||id,status||on[0]=facilities.status||$eq||Archived&filter[0]=id||$eq||4 the join condition gets omitted because the join key is not intercepted correctly, key value pair is coming as
key= join=facilities||id,status||on
value= facilities.status||$eq||Archived
But we actually need
key= join
value= facilities||id,status||on[0]=facilities.status||$eq||Archived