The Canucks were in a tough spot with the salary cap and Hronek's acquisition isn't helping in any case. He's currently on a bridge deal that's paying him an AAV worth $4.4M. He'll need a new contract by the end of 2024, just like Elias Pettersson.
At this point, it's hard to imagine that Hronek could even be worth this much, but if it turns out he is worth that much then the Canucks would really be in trouble. Quinn Hughes is the team's top defenseman and currently commands a $7.85M AAV, he still has terms to his contract. Oliver Ekman-Larsson also carries a hefty AAV since he represents $7.25M on the Canucks' book for 4 more years at the end of this one.
If the Canucks were to extend Hronek, at say, $7.5M, it would make their defensive top 3 the most expensive in the league. A trio made of, Hughes, Hronek, and OEL worth $22.6M.
On top of everything, the Canucks will need to ink their future captain Elias Pettersson and he'll definitely ask for a vital raise. Unless the Canucks find a way somehow to rid themselves of Ekman-Larsson's contract it'll be really hard for them to figure out a really competitive line-up with such salary restraints.