Deck and Coping separation

[Sharonja79]

I have a rectangular vinyl pool 14'x30' and for the past couple of years there is a slow separation between the deck and the coping brick around the pool
Image here:
https://mtsg-my.sharepoint.com/:i:/g/personal/events_mytechsupportguy_net/EXndNvR-1sxMsI1tp2UbRsQBAaFWVNbKEI-3hUZln5TPwg?e=FUFEki

The crack is about 3-4 inches deep and at some points 3/4 inch wide.
Any ideas how to fill/repair?

Thank you for your help.