Look at moving edges
Choose a pattern and follow an edge as it travels. Record whether a break, jump or uneven movement stays visible across several passes. Compare more than one speed so a one-off timing disturbance is not mistaken for a persistent display problem.
V-Sync and VRR
Browser animation does not expose the complete synchronization state of the operating system, graphics driver and display. A smooth-looking browser pattern cannot certify that G-Sync, FreeSync or another VRR mode is active. Check those settings in the relevant system or driver controls.
Compare the actual application
If the problem occurs in a game, compare that game under the same display and connection settings. An application's rendering and presentation path may behave differently from a browser. Keep the browser test as one observation rather than treating it as a complete diagnosis of the graphics pipeline.