I got another post on STEAM;
https://steamcommunity.com/app/1026680/discussions/0/1635291505041144048/It also mentions that with Reshade the game screen can eliminate "Black Bar" by OpenGL setting of Reshade.
But the game screen has no sign of Reshade when starting without noticing such as "Reshade 4.4.2 700 by crosier......" on upper-left corner.
I doubt that FFVIII.exe is not compatible with Reshade ?
As for my Video Card spec checked by OpenGL Extensions Viewer 6.0 is like below;
OpenGL 3.3 shall be handled by my VideoCard, so why Reshade could not be injected to FF8 REMASTERED as stated in steam community ?