That really depends on the technology used. For example, all modern Ethernet standards (which includes both copper and fiber optic) are full duplex, meaning they can provide the full bandwidth in both directions at once. So a gigabit Ethernet link can do a gigabit in one direction AND a gigabit in the other direction at the same time (but not two gigabits in one direction).
To be fair, giving a company that’s been failing to get themed icons to work on Android for almost four years now less than a month to make a significant change to a core part of their software is… quite weird?
Like, the EU usually gives companies at least half a year to comply with smaller demands than this, because companies with such a huge bureaucracy load wouldn’t even be able to change an app logo in such a short amount of time.