Update the proposed archive, check you got the version below, then purge your grub packages, and then reinstall the latest version that should fix your issue.
grub2 (2.02-2ubuntu8) bionic; urgency=medium * Drop debian/patches/mkconfig_keep_native_term_active.patch, which can lead to flickering between graphical and text mode when traversing the menu. (LP: #1752767) * debian/patches/yylex-explicitly_cast_fprintf_to_void.patch: Fix FTBFS with flex 2.6.4. -- dann frazier <da...@ubuntu.com> Sun, 04 Mar 2018 06:11:35 -0700 ** Changed in: grub2 (Ubuntu) Status: New => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1753272 Title: Weird grub boot display since Bionic To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1753272/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs