But then any TxPause frame will be dropped one. Load on RB is never higher than 20% (1gbps fiber).
Tx Flow control is enabled on purpose, I'm only surprised that such fast RB and still with pause frames.
Flow control does not know or care about your router load.
It only cares about congestion on the interface that its enabled.
Ethernet flow control is a mechanism for temporarily stopping the transmission of data on Ethernet family computer networks. The goal of this mechanism is to avoid packet loss in the presence of network congestion.
A sending station (computer or network switch) may be transmitting data faster than the other end of the link can accept it. Using flow control, the receiving station can signal the sender requesting suspension of transmissions until the receiver catches up. Flow control on Ethernet can be implemented at the data link layer.
In other words, if you don't like it, then disable it.
It baffles me how can someone enable a feature that they don't understand, and then proceed to say it's a bug.
More like B(ug)EBKAC...