1.58MHz is in the AM broadcast band. Maybe you mean 1.58GHz? (That's just 1,000 times the frequency, in a field in which 1/1000 of that frequency difference is enough to separate some signals.)
Since it's a Pixel, contact Google tech support and speak to them. They probably won't have any clue about what you're talking about, but you have to start with them. What you want is for them to get to engineering so engineering can tell them to replace your phone. (A phone interfering with GPS signals is so illegal that one company had to pull a product off the market for something like that.) They're pretty good about defective phones anyway, and if one of them is violating the law, not only will they replace it, they'll want to get their hands on it to make sure it doesn't ever happen again.
(Technically, the local oscillator in the GPS is putting out enough signal to be received by your spectrum analyzer. [It's probably at -30db, not 30db, which is still a whopping signal. Your phone signal is probably around -80db or even lower. A 30db signal at GPS frequencies would block out GPS reception for at least a few miles. 30dbw works out to 1,000 Watts.] The people who told you about it could explain it more fully, if you're interested.)