Purebrowser in amber on 19 Sep 2019, purebrowser/amber, now 68.1.0esr+really60.9.0esr-1~deb10u1pureos1 amd64, is on the system nearly unusuable because it never exits.
The window closes, but the instance persists, as evidenced by "ps -e | grep pure".
The problem seems to be that SQlite3.jsm does not want to exit.
Workaround is in {F334851}.