This is a Samsung Galaxy S8+ SM-G955FD with Oreo 8.0.0, today updated. Baseband G955FXXU4CRI1, Samsun Experience version 9.0, Android security patch level 1 November 2018.
Since this update, whenever Google Maps attempts to go into the background, it is killed. Always. It didn't happen before. Google Maps itself was not upgraded at that time. Its incredibly annoying, its impossible for example to share trip progress with someone, as when it opens Contacts, Google Maps is killed with a message "Maps has stopped, Open app again".
Other apps seem to be not affected, can go into the background and not get killed.