The vacuum sealing might be the problem. Under vacuum, water boils at a much lower temperature, and that could be affecting the fish. As far as the albumin, I know you can fix this with salmon by doing an ice water/salt brine for 30 minutes before cooking, but I think the fish would need to be thawed for it to work. Not sure if this will work for the albumin problem on the red snapper, but it might.
Here's what I would recommend... Take the fish out of the freezer, cut open the end of the bag to release the vacuum, and let it thaw in the fridge for a few hours. If you let it thaw while under vacuum, it will just compress the fish. After thawing, brine for 30 minutes, then put it back in the bag(no need to double the plastic waste), and put the bag into the water bath with the open end sticking up out of the water. Make sure the fish is totally submerged. Now fold the open end of the bag over the side of the pot, and use something like a binder clip or clothes pin to secure the open end of the bag to the side of the pot.
Doing it this way allows the water to push the air out from around the fish, and have the same contact as if under a vacuum seal. Folding the open end over the side of the pot prevents water from getting into the bag. If your fish floats, stick a table spoon in the binder clip, and it will force the bag down.
133 might be abit high of a temp for salmon, I usually cook mine at 125. I usually get farm raised. It has a texture like butter, it literally melts in my mouth.