I am seeing a flashing or flickering window when I try to open a file using
gvim <filename>
command.
I am not sure if it is Mac OS related problem. I have installed macvim using brew
(How can I install MacVim on OS X?).
Please do not flag this post though there exists a similar post: VIM Flashing Issue as the problem doesn't get resolved by following the answers (the most voted answer mentions a screenshot whose link is broken).
I'm using the latest macOS Mojave (10.14).