This is in the down stream direction (SFU -> Client).
SFU has to measure available bandwidth and adjusts what/how much it can send.
These logs could indicate either
1. Client's network cannot handle the amount of media traffic from SFU - most probable case
2. Server is overload/over driving its egress and causing congestion - this is self-inflicted by the server and should not happen as long as you are not overdriving the CPU/network.