Firejailed firefox process runs even after exiting firefox
I have configured firejail using apparmor and it's working fine. However, even after I close firefox there is a firejail firefox process as below:
~~> ps firejail
russellb 3958 0.0 0.0 7064 2276 pts/0 S+ 13:51 0:00 \_ grep firejail
russellb 3210 0.0 0.0 4472 2696 ? S 13:38 0:00 \_ /usr/bin/firejail /usr/bin/firefox
russellb 3211 0.0 0.0 4484 2376 ? S 13:38 0:00 \_ /usr/bin/firejail /usr/bin/firefox
This process keeps running until I kill manually with pid. Whereas this is not the case with other programs, eg: for pdfreader the process exits once I close the program.
Could someone explain why is this? Is this unusual for a default setup?