Union SG are from Brussels and they came within two minutes of being the best team in the country last year
You can leave out the "recently" as well since Anderlecht have 1 championship in the past 9 years, while Brugge have won 5 of the last 7 league titles. Anderlecht last won something 6 years ago and even then it was with terrible football, the fans wanted the coach (Rene Weiler) gone ASAP even though he did get results.
No right now they don't have what it takes. Their owner is a clown, even though he has deep pockets. Their president is an idiot who was no clue how to lead a professional football club and the fans hate him deeply. Their sporting director comes from a small Danish club and looks like he's in way over his head, and their scouting department seems non-existent these days if you see what they come up with. They also fired their head of youth development, an immensely popular guy who was born and raised in Brussels and spent a large part of his own youth and playing career at Anderlecht, and has been overseeing their youth teams for over 20 years now and helped develop the likes of Lukaku, Tielemans, Kompany, etc.. because he was too expensive
The only thing they have left is their name (that's why they are still able to sign a player like Kasper Dolberg for example) and their reputation as the best youth developing team in Belgium. But even when they have a good prospect on the way it seems they get signed away so quickly they can barely make a name for themselves in the first team (Jeremy Doku, Julien Duranville..)
Another problem they have is that every year they get overtaken by more teams at the top of the Belgian League. It used to be Anderlecht, Brugge and Standard Liege. But then came RC Genk and occasionally AA Gent. Now Antwerp has joined the top tier with their championship (and rich owner), followed by Union SG who look like they are here to stay (and backed by Brighton). The championship playoffs in Belgium this season will go back to 6 teams (it was 4 teams since the covid season) and it will be one hell of a fight for them to make that.
Right now it's really hard to see them being a contender for the forseeable future.