I think it’s worthwhile breaking down what your usage is. Your actual database size might not be so large, if most of your usage is uploads, and it’s only the database part which demands maybe 3x space during upgrade.
One thing you can check is the relative size of a backup with downloads compared to a backup without downloads.
Or, use the command line. Here’s some output from my rather small forum:
root@rc-debian-hel:~# free -m
total used free shared buff/cache available
Mem: 3813 1631 267 492 1915 1504
Swap: 4095 730 3365
root@rc-debian-hel:~# swapon
NAME TYPE SIZE USED PRIO
/var/local/swap/swapfile.1 file 1024M 730.2M -2
/var/local/swap/swapfile.3 file 1024M 136K -3
/var/local/swap/swapfile.0 file 1024M 0B -4
/var/local/swap/swapfile.2 file 1024M 0B -5
root@rc-debian-hel:~# df -h
Filesystem Size Used Avail Use% Mounted on
tmpfs 382M 1.2M 381M 1% /run
/dev/sda1 38G 22G 14G 62% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/sda15 253M 6.3M 246M 3% /boot/efi
overlay 38G 22G 14G 62% /var/lib/docker/overlay2/68abab42f48040e0dfc03d3c9fc893dfa3e7fb01ba1b2215731668339bbc3766/merged
tmpfs 382M 0 382M 0% /run/user/0
Looking closer:
root@rc-debian-hel:~# du -kx / | sort -n | tail -33
767000 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554/diff/home/discourse/.local/share/pnpm
767004 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554/diff/home/discourse/.local/share
767020 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554/diff/home/discourse/.local
795804 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554/diff/home/discourse
795808 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554/diff/home
833836 /var/discourse/shared/standalone/postgres_data
884648 /var/discourse/shared/standalone/uploads/default/original
978000 /usr/lib/modules
991644 /var/lib/docker/overlay2/68abab42f48040e0dfc03d3c9fc893dfa3e7fb01ba1b2215731668339bbc3766/diff
991664 /var/lib/docker/overlay2/68abab42f48040e0dfc03d3c9fc893dfa3e7fb01ba1b2215731668339bbc3766
1025164 /var/discourse/shared/standalone/uploads/default/optimized
1146528 /usr/lib/firmware
1350496 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554/diff
1350512 /var/lib/docker/overlay2/8b6ac2d69a1fa195285e61aba2876484a69fd2a19032c2f4def1c4adb02d6554
1909816 /var/discourse/shared/standalone/uploads/default
1919380 /var/discourse/shared/standalone/uploads
2471968 /usr/lib
2506940 /var/log/journal/82e4cf9bff9748d090b41e6d336353eb
2515140 /var/log/journal
2592200 /var/log
3029428 /usr
3839148 /var/discourse/shared/standalone/backups/default
3839152 /var/discourse/shared/standalone/backups
4194324 /var/local/swap
4194328 /var/local
5171844 /var/lib/docker/overlay2
5217052 /var/lib/docker
5455612 /var/lib
6682972 /var/discourse/shared/standalone
6682976 /var/discourse/shared
6685716 /var/discourse
19041368 /var
23037264 /
root@rc-debian-hel:~# du -kx /var/discourse/shared/ | sort -n | tail -33
42312 /var/discourse/shared/standalone/uploads/default/original/2X/f
42448 /var/discourse/shared/standalone/uploads/default/original/2X/1
42548 /var/discourse/shared/standalone/uploads/default/original/2X/6
43380 /var/discourse/shared/standalone/uploads/default/optimized/2X/2
44148 /var/discourse/shared/standalone/uploads/default/optimized/2X/5
44340 /var/discourse/shared/standalone/uploads/default/optimized/2X/1
45240 /var/discourse/shared/standalone/uploads/default/optimized/2X/e
46648 /var/discourse/shared/standalone/uploads/default/optimized/2X/c
49516 /var/discourse/shared/standalone/uploads/default/optimized/2X/8
49772 /var/discourse/shared/standalone/uploads/default/optimized/2X/9
49932 /var/discourse/shared/standalone/log/var-log/nginx
50788 /var/discourse/shared/standalone/uploads/default/optimized/2X/0
55428 /var/discourse/shared/standalone/uploads/default/optimized/2X/d
55844 /var/discourse/shared/standalone/uploads/default/optimized/2X/f
57548 /var/discourse/shared/standalone/uploads/default/optimized/2X/6
77280 /var/discourse/shared/standalone/log/var-log
81928 /var/discourse/shared/standalone/postgres_data/pg_wal
84064 /var/discourse/shared/standalone/log
294384 /var/discourse/shared/standalone/uploads/default/optimized/1X
325068 /var/discourse/shared/standalone/uploads/default/original/1X
559576 /var/discourse/shared/standalone/uploads/default/original/2X
724684 /var/discourse/shared/standalone/postgres_data/base/16384
730776 /var/discourse/shared/standalone/uploads/default/optimized/2X
749424 /var/discourse/shared/standalone/postgres_data/base
833836 /var/discourse/shared/standalone/postgres_data
884648 /var/discourse/shared/standalone/uploads/default/original
1025164 /var/discourse/shared/standalone/uploads/default/optimized
1909816 /var/discourse/shared/standalone/uploads/default
1919380 /var/discourse/shared/standalone/uploads
3839148 /var/discourse/shared/standalone/backups/default
3839152 /var/discourse/shared/standalone/backups
6682972 /var/discourse/shared/standalone
6682976 /var/discourse/shared/