The report says, "We concluded that, in the outer reaches of the solar system, and even considering the large uncertainties associated with the abundance of Borisov-like objects, transitory interstellar comets should outnumber Oort Cloud objects (comets from our own solar system)," Siraj added."
Consider that a comet traveling 13 light years at 20 km/s, could take 195,000 years to travel that distance. We also have the statement, *transitory interstellar comets should outnumber Oort Cloud objects...*
There is also the calculated number of Oort Cloud comets said to exist today. Different reports measure the numbers in the range of trillions of comets.