In my case I found what caused the problem. When I start Pure Maps, it tries to get map tiles from OSM Scout Server, but that apparently was uninstalled due to missing libicuuc.so.63, and systemd keeps trying to start it. The journal is full of the following lines over and over:
systemd[2115]: osmscout-server.service: Main process exited, code=exited, status=203/EXEC
systemd[2115]: osmscout-server.service: Unit entered failed state.
systemd[2115]: osmscout-server.service: Failed with result 'exit-code'.
systemd[2115]: Started OSM Scout Server.
# and
systemd[23709]: osmscout-server.service: Failed at step EXEC spawning /usr/bin/harbour-osmscout-server: No such file or directory
~/.config/systemd/user/osmscout-server.service is still left, even if OSM Scout Server has been uninstalled. I will remove this service file and use some other maps until a new OSM Scout Server is available.