What's this ugly screen and how to get rid of it?

Probably some missing splash image, this is ugly as hell every time booting up.

yes its just one sec ! happens in some cases - nothing wrong - dont worry :wink:

BTW: which board and OS installed ?

It’s VIM3, tried multiple Linux build, Ubuntu and Debian, all running from SD card. I don’t remember seeing this before I wiped out the original Android.

Yes, only exist with mainline uboot + mainline kernel.

I had the same issue, its only a bad outdated khadas image.

Even with that ksecure image you will be faced with resetting bootloader which killed my hole setup

Your best to find an update image