One to many broadcasting question

From: https://mediasoup.org/documentation/v3/scalability/#one-to-many-broadcasting

If the encoder receives many PLIs or FIRs (although mediasoup protects the producer endpoint by preventing it from receiving more than one PLI or FIR per second) the sending bitrate of the broadcaster endpoint would increase by 2x or 3x. This may be a problem for the producer endpoint and also for viewers that will receive much more bits per second.

So if I use a GOP size equal to 1 second, there is no need to re-encode the stream, because of the PLI/FIR limit. Is it right?

Yep. If your endpoint sends key frames every 1 second it can even ignore PLIs/FIRs anyway. The problem is that the bitrate may be too high due to so many key frames.