I recently upgradet from Version 3 to 4 and encountered some bugs:
1. When appending / linking a Material / Object from a Blendfile created in previous Version (3.07) the Material Inputs of the Mix Material gets swapped, which makes the Material look wrong.
2. When "Node Graph Upload Optimization" is enabled, changing Values "Ray Epsilon", "Path Term Power", "Coherent Ratio", "Caustic Blur" won't take effect after Preview Samples Count is reached
3. Ray Epsilon minimum Limit isn't the same as in Standalone. Pressing the arrow icons in the number field flips basically from min to max Limit without any intermediate steps.
4. GPU Memory Display in the Renderview Window is totally akward and wrong.