A possible workaround:
The quicksave function continues to work after the screen freeze. I was able to quicksave the game after Rym destroyed the bridge.
After force-closing and relaunching the game, I loaded the quicksave and was able to continue with the Rym fight.
Hopefully, this works for others.
The bug that is causing this issue is a graphics problem related to lightning effects.
The same issue that freezes the game when Ryn uses a lightning bolt to destroy the bridge happens when you equip the armour Deltro's Cage, which also has a lightning effect.
I've tried to disable graphics as much as possible but the issue occurs with Steam updated version of POE 2 and updated Radeon drivers.