Some users report VRAM leaks after 2+ hours of driving. Restarting the game fixes it. SCS is aware.

in beta, subsequent patches have aimed to stabilize the increased graphical load. Comparison with Subsequent Versions

The 1.50 update introduced a new rendering core, which may lead to specific performance or visual regressions: Performance Drops

To report a bug in Euro Truck Simulator 2 (ETS2) version 1.50, you should post a detailed description along with your game log to the official SCS Software Bug Forum Steps to Create a Bug Report Find Your Game Log : Locate the game.log.txt file in your Documents/Euro Truck Simulator 2 Upload the Log