That's easy to fix:
Step 1:
sudo tee /etc/tmpfiles.d/mglru.conf <<EOF
w- /sys/kernel/mm/lru_gen/enabled - - - - y
w- /sys/kernel/mm/lru_gen/min_ttl_ms - - - - 300
EOF
Step 2:
apt install zram-tools
sed -i 's/#PERCENT=.*/PERCENT=130/' /etc/default/zramswap
I'm on an older LTS kernel so no support for lru_gen but I will definitely check out zramswap - thanks.