Pyrosm python package: how to filter?

Hello,

I'm using the pyrosm package in python and I read with it a bdf file for Bristol city. I want to filter and query all the shops and couple of amenities. However, every time I filter only for all shops I've 3,367 records. When I filter for all shops and some amenities, instead of having more records I have less (2,059). It seems in the data that I miss some of the shops. Below my code.

from pyrosm import OSM
osm_path ='bristol-latest.osm.pbf' # downloaded from geofabrik
osm = OSM(osm_path)
custom_filter = {"shop":True, "amenity":["bar", "cafe", "fast_food", "ice_cream", "pub", "cinema"]}
pois = osm.get_pois(custom_filter=custom_filter)

Any idea what's wrong please?

Thank you.