We get blurriness when we render translucent materials with Disable Depth Test Enabled, and when these materials have other opaque geometry in front of them. The issue is in Both UE4.27 and 5.03.
Quite visible in the Editor.
not so visible, but still there in Standalone Game mode
Replicatable in both Forward Shading and Deferred.
Output Velocity for the material is Enabled
UE 5.00 Video (looks the same on 4.27):