Occasionally, for no apparent reason, I cannot see under water. To be clear, this starts upon opening the world, so if I am able to see under water at one point, I know I will be able to see later. But when I enter the water for the first time upon opening the world, I often find I cannot see anything but pitch black upon entering the water--not darkness, pitch, opaque black. If, upon discovering the glitch, I close and reopen the app, the issue goes away, and I can see things underwater like normal. I have no idea how to trigger the glitch, but I don't want this problem to get worse.
EDIT: What I'm seeing in the comments makes me believe that this problem applies to ALL of Minecraft Bedrock, not just the FireOS version.