Is this related to the other issue you posted about? AKA it happened about the same time?
Have you installed the 2023.1.4 Update yet? ABOUT command will confirm what you have installed. If not, get it from your Autodesk Account Page here https://manage.autodesk.com/cep/#products-services/updates
Restart your PC afterwards.
If that did not help... Set GFXDX12 variable to 0 (that's a zero) then restart AutoCAD/LT..
Also consider turning off LINESMOOTHING and LINEFADING variables.
If still no relief then start GRAPHICSCONFIG command and change the 2D Display Settings pulldown from "advanced mode" to one of the other choices.
If all else fails, then turn off Hardware Acceleration as a last resort. Any difference?