Several gb's of leftovers clogging up / after update to 20

Successfully updated to version 20 in NextcloudPi Docker, but I now have several gb’s of unknown data in /var/ clogging up my small 8gb / partition. / was around 50% full and now it is 100% full post-upgrade. Looking for suggestions on how to clean it up. Here is what you see inside the Docker container.

# df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay         7.2G  6.9G     0 100% /
tmpfs            64M     0   64M   0% /dev
tmpfs           952M     0  952M   0% /sys/fs/cgroup
shm              64M     0   64M   0% /dev/shm
/dev/mmcblk1p1  117G  6.1G  105G   6% /data
/dev/mmcblk0p1  7.2G  6.9G     0 100% /etc/hosts
tmpfs           952M     0  952M   0% /proc/asound
tmpfs           952M     0  952M   0% /sys/firmware

$ sudo du -sh /var/*
892K	/var/backups
96M	/var/cache
6.3G	/var/lib
4.0K	/var/local
0	/var/lock
892K	/var/log
2.6M	/var/log.hdd
4.0K	/var/mail
4.0K	/var/opt
0	/var/run
16K	/var/spool
12K	/var/tmp

I’m unsure on where to look in regards to cruft left over from the upgrade on my boot disk.