here is output from cat proc/mounts:
teddy@teddy-GWTN141-10:~$ cat /proc/mounts
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev devtmpfs rw,nosuid,noexec,relatime,size=8037548k,nr_inodes=2009387,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,nosuid,nodev,noexec,relatime,size=1613536k,mode=755 0 0
/dev/sda6 / ext4 rw,relatime,errors=remount-ro 0 0
securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
tmpfs /run/lock tmpfs rw,nosuid,nodev,noexec,relatime,size=5120k 0 0
tmpfs /sys/fs/cgroup tmpfs ro,nosuid,nodev,noexec,mode=755 0 0
cgroup2 /sys/fs/cgroup/unified cgroup2 rw,nosuid,nodev,noexec,relatime,nsdelegate 0 0
cgroup /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,xattr,name=systemd 0 0
pstore /sys/fs/pstore pstore rw,nosuid,nodev,noexec,relatime 0 0
efivarfs /sys/firmware/efi/efivars efivarfs rw,nosuid,nodev,noexec,relatime 0 0
none /sys/fs/bpf bpf rw,nosuid,nodev,noexec,relatime,mode=700 0 0
cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpu,cpuacct 0 0
cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
cgroup /sys/fs/cgroup/rdma cgroup rw,nosuid,nodev,noexec,relatime,rdma 0 0
cgroup /sys/fs/cgroup/hugetlb cgroup rw,nosuid,nodev,noexec,relatime,hugetlb 0 0
cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0
cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
cgroup /sys/fs/cgroup/net_cls,net_prio cgroup rw,nosuid,nodev,noexec,relatime,net_cls,net_prio 0 0
cgroup /sys/fs/cgroup/pids cgroup rw,nosuid,nodev,noexec,relatime,pids 0 0
cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
systemd-1 /proc/sys/fs/binfmt_misc autofs rw,relatime,fd=28,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=19526 0 0
mqueue /dev/mqueue mqueue rw,nosuid,nodev,noexec,relatime 0 0
hugetlbfs /dev/hugepages hugetlbfs rw,relatime,pagesize=2M 0 0
debugfs /sys/kernel/debug debugfs rw,nosuid,nodev,noexec,relatime 0 0
tracefs /sys/kernel/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0
fusectl /sys/fs/fuse/connections fusectl rw,nosuid,nodev,noexec,relatime 0 0
configfs /sys/kernel/config configfs rw,nosuid,nodev,noexec,relatime 0 0
/dev/loop1 /snap/gnome-3-34-1804/66 squashfs ro,nodev,relatime 0 0
/dev/loop2 /snap/gtk-common-themes/1514 squashfs ro,nodev,relatime 0 0
/dev/loop0 /snap/core18/1988 squashfs ro,nodev,relatime 0 0
/dev/loop3 /snap/core18/2074 squashfs ro,nodev,relatime 0 0
/dev/loop4 /snap/snap-store/547 squashfs ro,nodev,relatime 0 0
/dev/loop5 /snap/gtk-common-themes/1515 squashfs ro,nodev,relatime 0 0
/dev/loop7 /snap/snapd/11036 squashfs ro,nodev,relatime 0 0
/dev/loop6 /snap/snap-store/518 squashfs ro,nodev,relatime 0 0
/dev/loop8 /snap/snapd/12159 squashfs ro,nodev,relatime 0 0
/dev/loop9 /snap/gnome-3-34-1804/72 squashfs ro,nodev,relatime 0 0
/dev/sda1 /boot/efi vfat rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 0
tmpfs /run/user/1000 tmpfs rw,nosuid,nodev,relatime,size=1613532k,mode=700,uid=1000,gid=1000 0 0
gvfsd-fuse /run/user/1000/gvfs fuse.gvfsd-fuse rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0
/dev/fuse /run/user/1000/doc fuse rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0
tmpfs /run/snapd/ns tmpfs rw,nosuid,nodev,noexec,relatime,size=1613536k,mode=755 0 0
nsfs /run/snapd/ns/snap-store.mnt nsfs rw 0 0
/dev/sdb1 /media/teddy/Ubuntu\04020.04.2.0\040LTS\040amd64 iso9660 ro,nosuid,nodev,relatime,nojoliet,check=s,map=n,blocksize=2048,uid=1000,gid=1000,dmode=500,fmode=400 0 0
/dev/sdb3 /media/teddy/writable ext4 rw,nosuid,nodev,relatime 0 0
I have plenty of disk space but it seems the reinstall partitioned a 16 GB drive which is running out of space. I didn't even have enough room to make a screenshot of the graphical representation from the Disks app.
