How to fix: The "nat" table is not intended for filtering, the use of DROP/ALLOW is therefore inhibited.

This output/error was caused by running:
iptables-restore --test /etc/iptables/rules.v4
The file content was:
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
COMMIT
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A OUTPUT -d 202.91.162.0/24 -j DROP
-A OUTPUT -d 202.91.163.0/24 -j DROP
-A OUTPUT -d 202.91.160.0/24 -j DROP
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -i eth0 -p udp -m multiport --dports 12345 -j DNAT --to-destination 10.8.0.2
-A POSTROUTING -o eth0 -j MASQUERADE
COMMIT
It should be:
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A OUTPUT -d 202.91.162.0/24 -j DROP
-A OUTPUT -d 202.91.163.0/24 -j DROP
-A OUTPUT -d 202.91.160.0/24 -j DROP
COMMIT
# Completed on Thu Oct 10 15:40:48 2024
# Generated by iptables-save v1.8.7 on Thu Oct 10 15:40:48 2024
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -i eth0 -p udp -m multiport --dports 12345 -j DNAT --to-destination 10.8.0.2
-A POSTROUTING -o eth0 -j MASQUERADE
COMMIT
problem was me inserting that -A OUTPUT * DROP rules into wrong section of the file (under *nat section, not under *filter section)