I have gigabit fibre internet. In the 2 years I’ve had it (with the exception of MSFS), I’ve never seen downloads from anywhere, any time, come in at less than 750-800 Mbits at slowest. In most cases, I clock in at the mid 900s. Steam included here. It basically saturates my available bandwidth. Even downloading stuff from MS via my MSDN / Visual Studio subscription.
MSFS is the one exception for me where it struggles to use even 10% of my available bandwidth. And it wasn’t always like this. The first few months after launch, I was seeing speeds to 500-600 Mbits downloading MSFS content. It was super fast. It was with the January 2021 update (can’t remember what the official name for it was) which saw this break and I was lucky to be seeing 20 Mbits. Since SU4, I’m back to seeing about 80-100 Mbits, with the occasional spike up to 120 or so when downloading the larger files.