Hello,
There was a high traffic towards one of my server. Let's say the IP address of that server is 1.2.3.4. I tried to create a firewall rule that accepts the traffic (forward chain, dst address = 1.2.3.4) just to see the statistics. What I don't understand is why the RX rate is different between firewall statistics and torch?

You did not include the firewall rule, which is necessary for any rational attempt at analysis. Preferably, all firewall rules, so that applicable prior rules can be inspected as well.

You will note that the number of packets is wildly different as well. Clearly the firewall rule isn't doing what you envision it doing.

Hello,
The firewall rule is simple like this

Please post the full /ip firewall filter export output. The order of the rules is important. The traffic you are watching may match another rule that is placed earlier than the one you are watching.