I am using DarkBlade12's Particle Effect API, when I send 1.8 block crack packets to the users, 1.8 users are able to see it while 1.7 users are not. If I switch from using ViaRewind to an old ProtocolSupport 1.8.8 build, the particles are visible to 1.8 and 1.7 users like it should. I would definitely rather use ViaRewind though over ProtocolSupport because I believe some 1.7 users are having connectivity issues now that I switched to ProtocolSupport.

Fixed with 2b79187

Could you provide the your code to send the particles? A vanilla /particle command would be even better.