Ah - but ‘which’ ebay pcb antenna do you have?
There is the short antenna - either naked or in a PVC case
This one with an elevated feed
this one with elevated feed and tuned lower elements
I use three of ‘elevated feed, not trimmed’ types. Not because they are great antennas, but because they are repeatable.
I can then run a legitimate comparison between two receivers, filter vs no fiter etc.
The point is I can (as far as possible) reduce my comparison down to one variable.
Comparing different antennas feeding different filters into different receivers and expecting it to tell you anything meaningful about an individual component is just silly.