I have the same problem as Heinrich Schuchardt (same version of cups-browsed, but cups-daemon 2.2~rc1-4 from experimental).
$ sudo systemctl stop cups-browsed.service
takes 90 seconds (while avahi-daemon.service and cups.service are still running). journalctl shows
Aug 21 14:38:52 macarthur sudo[16227]: pam_unix(sudo:session): session opened for user root by roderich(uid=0)
Aug 21 14:38:52 macarthur systemd[1]: Stopping Make remote CUPS printers available locally...
Aug 21 14:40:01 macarthur CRON[16255]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 21 14:40:01 macarthur CRON[16260]: (root) CMD ([ -x /usr/sbin/dma ] && /usr/sbin/dma -q1)
Aug 21 14:40:01 macarthur CRON[16255]: pam_unix(cron:session): session closed for user root
Aug 21 14:40:22 macarthur systemd[1]: cups-browsed.service: State 'stop-sigterm' timed out. Killing.
Aug 21 14:40:22 macarthur systemd[1]: cups-browsed.service: Killing process 1630 (cups-browsed) with signal SIGKILL.
Aug 21 14:40:22 macarthur systemd[1]: cups-browsed.service: Main process exited, code=killed, status=9/KILL
Aug 21 14:40:22 macarthur sudo[16227]: pam_unix(sudo:session): session closed for user root
Aug 21 14:40:22 macarthur systemd[1]: Stopped Make remote CUPS printers available locally.
Aug 21 14:40:22 macarthur systemd[1]: cups-browsed.service: Unit entered failed state.
Aug 21 14:40:22 macarthur systemd[1]: cups-browsed.service: Failed with result 'signal'.
--- /lib/systemd/system/cups-browsed.service ---
[Unit]
Description=Make remote CUPS printers available locally
Requires=cups.service
After=cups.service avahi-daemon.service
Wants=avahi-daemon.service
[Service]
ExecStart=/usr/sbin/cups-browsed
[Install]
WantedBy=multi-user.target
---
--- /lib/systemd/system/cups.service ---
[Unit]
Description=CUPS Scheduler
Documentation=man:cupsd(8)
[Service]
ExecStart=/usr/sbin/cupsd -l
Type=simple
[Install]
Also=cups.socket cups.path
WantedBy=printer.target
---