When switching back from Fancy graphics to Vibrant Visuals, the water incorrectly turns into the “Fancy” water, not the one from Vibrant Visuals. This causes the water to become unfathomably saturated and also causes the reflections to mess up unless under it, at which it acts like Vibrant Visuals water.
Thank you for your report!
However, this issue is already being tracked in MCPE-221698, so I'll be resolving this one as a Duplicate.
This bug is already fixed in the Preview version for Minecraft 26.0, and should hopefully make it to the full drop next year!
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