API Frame SetFlattensRenderLayers

Controls whether all subregions are composited into a single render layer. Frame:SetFlattensRenderLayers(flatten)

• flatten: - If true, enables render layer flattening.

• When enabled, all descendant textures and fontstrings will be flattened into a single "layer" for rendering. This can be used to prevent a visual effect where unrelated overlapping frames appear to render interleaved with one another.
• This function only controls an explicit request for render layer flattening. Render layer flattening can also be enabled implicitly through other frame attributes and APIs.