Flicker on vim 9 startup

Hi,

On starting vim 9, windows 10, there is a very brief flicker visible. Light flash before normal service is resumed (colour scheme space-vim-dark). Without this plugin there is no flash.

Reproduce the brief startup flash with Vim 9 on Windows 10, using vim-startify and the space-vim-dark colour scheme. Compare startup with and without the plugin, then trace the startup path to identify the source of the flicker; done means the flash no longer appears.

Written by the indexing model from the issue text.