We haven't even met the guy
I guess it's because there was a mini scene where a man (assumed to be Karasuma Renya) was on the train where Conan solved a case. Soon after Conan left the train and met Amuro there by coincidence, Amuro gets a call which says to investigate Conan.
That was rum
Correction: Conan didn't meet Amuro but he boarded from the same station
https://www.mangago.zone/read-manga/detective_conan/mr/mk_v-3-chapter-1115/pg-16/
I saw some spoilers that karasuma renya already knows Conan's identity. Which chapter was it?