When placing slabs and stairs underwater, when looking at the block from certain angles, a random air gap can appear despite one not being there. (Screenshot 'Bug 1')

Also, when looking at waterfilled slabs or stairs through glass, their sides begin to flicker. (Screenshot 'Bug 2' - visual glitch can be spotted in the bottom corners of the screenshot beneath the glass walls, the blocks that are glitching are the underside of stone stairs but, as stated, occurs on the sides of slabs too)