Quick answer: Unity SSR (Screen Space Reflections) cleanly visible head-on but disappearing at grazing angles? SSR depends on what’s on screen; grazing rays exit the screen and return no hit — expected behavior.
Water at lake’s edge looks fine; at grazing distance you see no reflection — just the base water material.
SSR Limitations
SSR ray-marches in screen space. Rays leaving the viewport return no hit — grazing reflections of off-screen objects look wrong or vanish. Inherent to the technique.
Fade at Edges
HDRP SSR volume override has Screen Fade. Smoothly blends SSR to reflection probe / sky at screen edges so the disappearance is gentle, not popping.
Reflection Probes Fallback
Bake reflection probes for the area. SSR overlays where it has data; probes fill the rest. Convincing combined look.
Ray-Traced Reflections
For RT-capable hardware, ray-traced reflections look perfect at any angle. Costs more but no off-screen problem.
Verifying
Reflections look continuous at all angles. SSR fills the high-quality center; probes fill the edges.
“SSR can’t see off-screen. Fade to reflection probes at the edges.”
Bake reflection probes in every reflective scene — combined SSR + probe is the industry default for a reason.