Carballing sport 'em up Rocket League has disabled loot boxes which require keys to open for players in Belgium and the Netherlands. If you're there, you won't be able to open 'em, and that's that. While many countries are still eyeing paid loot boxes with suspicion, forming committees and signing declarations but not taking much action, Belgium and the Netherlands are going after the types of loot boxes they consider illegal gambling. These aren't blanket bans on all loot boxes but have hit digicrates in FIFA Ultimate Team, Overwatch, Counter-Strike: Global offensive, and more since the crackdown started in 2018.
Yesterday's patch notes said, plain and simple, that "Players in Belgium [and the Netherlands] can no longer open Crates with Keys due to government regulations." Bish bash bosh. Rocket League's loot boxes mostly contain cosmetic doodads to decorate cars.
I believe the 'Decryptor', a type of omnikey found while playing during certain events or through the Rocket Pass, still works. But opening regular crates with regular paid keys is a no-go. Unless you or hand 'em to a trusted friend in another country to open then hand back, or use a VPN to pretend you're elsewhere.
That would be the opposite of what some Apex Legends players did with Belgian loot box laws. When players discovered folks in Belgium got crafting materials instead of some loot boxes in the game's Battle Pass, which could be used to directly craft desired items rather than rely on luck, they changed their location to Belgium to benefit from those better drops.
The Belgian and Dutch laws aren't against microtransactions or loot boxes in general, only ones that they consider illegal gambling. In 2018, the Belgian Gaming Commission detailed what makes some loot boxes gambling in their eyes. Basically, because it's in a game and you're paying for a random chance for something that can be better or worse (rarer items being more desired, and therefore better), it's too much for them. They're fine with freebie random loot boxes, which actually meant they approved of the revamped digicrates in Star Wars Battlefront II - the game which really fuelled loot box backlash.
They're not interested in the effects loot boxes have on game design or any of that. They're not doing this for the good of video games, and I wouldn't expect them to. They're simply saying hey, some of these loot boxes are gambling, and that's not okay.
Industry bodies including the Entertainment Software Association and International Game Developers Association continue to broadly insist, hey, it's fine, we're doing nowt, and if we were we could regulate ourselves so don't worry about laws or anything. Belgium and the Dutchies disagree.
Yesterday's Rocket League update also added the drop rates of items to the Crate Preview Screen, so people where loot boxes are still available can see how low the odds are of getting something good. Psyonix publicly revealed drop rates in 2018 but showing them in-game is a lot better than away in a blog post somewhere.