This setting does not survive restarts. To make it persistent, I created a drop-in sysctl file /etc/sysctl.d/91-opmobiili.conf to contain the setting over restarts.
It looks like the op-mobiili devs forgot to remove debugging before publishing the app. If the QC is that sloppy, I wonder what else they may have forgotten, as end users should not need to do any tracing ever for a production released app.