this is why you remove the battery of the burner until you use it. remove the battery and sim of your compromised phone
relocate yourself install sim and battery of your burner
If the legit phone goes off while the burner is on that's a pattern.
If the legit phone goes off and (travel time / distance) elapses before burner appears (travel time / distance) away from the last legit ping that's a pattern.
If the legit phone and burner phone hit the same towers at the same time more than 3 times that's a pattern.
If the burner phone spends most of the time off (battery out, faraday cage etc) then the times it does connect are even stronger signals.
You need to generate a ton of "noise" data where both phones are hitting different towers at the same time on a constant basis; and never being together. Maybe mailing the burner phone on a regular basis between isolated locations that the real phone never goes to?
Cell tower data is incredibly powerful for tracking people.
Is this baked in to the infrastructure so you can be located or baked into the phone so you can locate yourself? If the former, I would have expected more concern?
"I would have expected more concern"
From the public? Everyone carries a phone, pretty much everyone is on Facebook. Given a yes/no box to tick you're going to get a lot of "yes" to "do you think you should have freedom from being tracked", but given a choice of what hardware/software to use people are going to pick the ones which everyone else is using, so that they can contact them. Next to nobody is going to stop at 4g because 5g has a higher granularity of location awareness.
the still detectable pattern depends on how often you use your phone or make the switch. its not a pattern if its done over days or if you even leave a phone cached in a special place such as a geocache so it can be swapped by someone else for a different burner.
