In an expanding universe things like distance and speed become ambiguous at large distances, with several sensible definitions that all give the same results under normal circumstances suddenly disagreeing. When it comes to distance, this is due to the expansion of space changing the scale of the universe while light is traveling towards us, so effectively changing things in the middle of our measurement. When it comes to speed, it is due to the difference between things moving apart because of their own motion, or things moving apart because new space appeared between them.

As a rough analogy for the former, imagine two ants separated by a piece of string they can walk along, but they're currently standing still. Now someone cuts the string and splices in a much longer piece of string between the ants. The ants didn't move, but now the distance between them (along the string = through space, in this analogy) is much longer. Does that mean the ants had a huge relative velocity when the splicing took place?

It's up to you, really, but I think most of us would prefer to factor out the expansion part and only include the moving part in the definition of velocity. In cosmology, this definition of speed is called peculiar velocity, and would not be particularly lage for two objects on opposite sides of the observable universe.

All of these complications go away if you only look at nearby objects. It's relative speed between two objects close to each other that's limited to 299792 km/s.