Ah, understand now. Which allows me to bring out a story from Canada which, while only vaguely related, might show that there's more available to an immigration officer than what's in a current passport.
I've been visiting Canada all my adult life, spread over maybe 5 or 6 passports. In the early '90s I studied there and had a Student Visa from Canada. Fast forward to about 2016 when I was very regularly visiting Canada for business and I used to be regularly invited to speak to the good people in the booths behind the main ones to be grilled to see if I was 'working' in Canada. In the course of one of those interviews the officer noted the fact that I had a student visa from 1991 to 1992 and was working in Canada for a year after that (as I was entitled to). I got through unscathed that time, and every time ...
So the Canadians at least had stitched together my total visit history across several passports and it was there on the screen. Not so difficult or unexpected I guess, but I dare say the US and most countries who are very particular about people entering their countries have a lot of behind-the-scenes information compiled about prospective visitors. I wouldn't be surprised if any airline reservation made on the various booking engines such as Amadeus, Sabre etc was available to them (fair means or foul) and compiled for each visiting pax.
Which is a long way of saying I don't think that they would be 'suspicious' of new passports because they would have proxy information on one's past travel history in their system anyway. (Or maybe I'm way overthinking it
)