Screen glitching since upgrading to Mojave

Hi, since upgrading my computer to Mojave I've had issues with the screen glitching upon startup. Usually consisting of white/black horizontal lines and the like when booting with the Apple logo. The computer otherwise boots up fine, but I'm worried this may lead to more serious issues further down the road. I noticed people suggested FileVault might be the reason, but I have that disabled so that's out. Any other ideas?