My anecdotal experience as a diver in Sweden that do a few ocean clean days per year, and who have operated during the periods of before, during and after a plastic bag ban, my experience has been that the ban worked greatly in reducing bags and plastic eating tools to a very major degree. Before the ban we saw plastic garbage practically every single dive, and the days we were cleaning we picked up bags of it by the end of the day. In contrast, plastic garbage is now thankfully rather rare to see, maybe once every 10th dive, and the effect has continued after the ban was lifted (so far). On cleaning days we might get like a few items in total. Plastic is no longer a major thing we pick up, and focus is instead on e-scooters and cans of laughing gas. In the couple ocean clean up events we have found more scooters than plastic bags.

I have seen a few canvas bags, but they don't seem to last long under the water.