My PC sometime complain about high load on the USB port - even if I have an active USB hub. When it complain it freeze and I have to use the Reset button to restart it.
If by “an active USB hub”, you mean one that is powered with a separate 5 V supply, then that is the same problem cited when you are advised not to connect a 5 V regulated supply to the UNO “5V” terminal when the USB is connected to a PC. This does not apply to a Nano, no such problem.
Most powered USB hubs (even “branded” ones) connect all output 5 V lines together with the 5 V from the external supply and the USB input and thus may “backfeed” the PC’s USB port causing that problem and possibly permanent damage.
So there is a warning about doing this on the UNO but it is somewhat surprising that such a problem is not frequently reported with the powered USB hubs which one would expect to be far more commonly used than Arduino UNOs.