updatedb does not prune paths

I have a timeshift user with backups in my /home. Every time after boot when I search for something with **locate**, all the timeshift directories are shown to me. To fix this issue, I added /home/timeshift to the PRUNEPATHS variable in /etc/alternatives/updatedb. I'm running Debian 10. On Arch I had the same issue and resolved it by adding the path to /etc/updatedb.conf. On Debian I don't have this file, so I changed /etc/alternatives/updatedb. When running updatedb manually after boot, locate doesn't show me the PRUNEPATHS anymore. But when I first start the system, updatedb shows me my /home/timeshift. Changing PRUNEPATHS in /etc/cron.daily/locate does not help either.