You can’t really call it false advertising when we weren’t really expecting more than brief cameos from either of them, but Wong and Abomination’s involvement in Shang-Chi and the Legend of the Ten Rings literally amounts to the footage in the trailer with an added couple of seconds.
It’s never explained why Doctor Strange’s closest confidant and Bruce Banner’s arch-nemeses have decided to take a break from whatever they were doing to participate in an underground fight club, a battle that Wong wins by having Emil Blonsky’s gamma-radiated alter ego punch himself in the face. It’s all very bizarre, especially when they disappear through a portal together, making it clear that they’re more than familiar with each other.
Wong will return in Spider-Man: No Way Home and Doctor Strange in the Multiverse of Madness, while Tim Roth was confirmed for She-Hulk a long time ago. So it is all connected? The short and somewhat confusing answer is yes, and no. It isn’t made clear where they’ve headed back to, but the bland and unassuming other side of the portal could be the Raft, the all-purpose prison for supervillains and other nefarious beings.
Why Wong decided to take a top-level prisoner out of containment to fight them for money isn’t explained, so it’s generated a lot more questions than it’s given answers. It could all be tied to Thaddeus Ross somehow, who’s been involved with both Abomination and the Raft in MCU canon, or maybe Blonsky has information that Wong needs and he’s doing him a favor by getting him a little R&R before he plays ball. Either way, it’s a random subplot definitely worth keeping an eye on as Phase Four continues.