With the latest RPR v 2.0.94 it seems that an animated particle system is not affected by motion blur.
I can confirm that on normal mesh objects that are not part of a particle system that RPR v 2.0.94 does apply motion blur to those.
e.g.
![pastedImage_1.png pastedImage_1.png](/t5/image/serverpage/image-id/6156iC48C2B1A693B9D91/image-size/large?v=v2&px=999)
The above is working fine in RPR.
This is the effect for the firework file (sample attached) in Cycles (with Motion Blur set to 0.1):
![pastedImage_2.png pastedImage_2.png](/t5/image/serverpage/image-id/6157i315DDBD818238B91/image-size/large?v=v2&px=999)
This is the RPR version with motion blur set to 1.0:
![pastedImage_3.png pastedImage_3.png](/t5/image/serverpage/image-id/6158i160AF0C6199814B4/image-size/large?v=v2&px=999)
A sample file is attached with all of the above settings saved for Cycles and RPR rendering engines.
You may need to run the animation in solid mode a couple of times to cache the frames before rendering with the other engines if Blender looses the explosion animation cache - but this isn't always the case.
Images have been packed.
Update:
The motion blur is expected to ONLY appear on Final Render (F12) and not in interactive preview rendering. None of the engines seem to offer preview motion blur.
Here is a screenshot of Cycles final verses Preview (an expected result):
![pastedImage_1.png pastedImage_1.png](/t5/image/serverpage/image-id/6164iB8D428EADC072E22/image-size/large?v=v2&px=999)
The bug is that RPR renders like Cycles preview even in Final F12 despite the Motion Blur setting being applied.