i only ever notice this when i install both iris and vics point blank.
water sometimes becomes more opaque depending on where i am or if im holding things. Corrinedev (vpb fork dev) says that the only shader stuff in vpb is the PIP scopes, but this can still happen if im not holding a gun, and he also suggested that it might be a geckolib issue.
version is 1.20.1 forge, all mods are latest on curseforge.