Combine two formulas for multiple inputs

I'm attempting to figure out how to combine these two formulas when there are multiple inputs.

Example inputs:

https://tracking.com/123456789https://tracking.com/123456789?ABCD

=SUBSTITUTE(SUBSTITUTE(XXX,"http://tracking.com/",""),"?ABCD","")

=REGEXREPLACE(XXX,"https://tracking.com/",)

Output should only show: 123456789

Does anyone know how to make this work?