It’s flickering out even when there is nothing to Z-fight with…
/me sighs
It’s crappy video drivers, it’s happening because the line is falling too well between floats that the video card is ‘optimizing’ it out instead of following the (admittedly ancient part here) of the OGL spec.
I don’t think that one is fixable without changing to an entirely new format like a texture overlay or a shader or so, it’s a driver bug.
What GPU does @Bear989Sr use anyway?