Flashing white lights on screen during PP ride?

Did a couple of PP rides yesterday for the first time in a few weeks. In both (Maria was one) there were round white lights constantly flashing on screen, seemingly coming from the other riders. I started in Neokyo so thought this was some night time lighting effect, but it persisted when I switched to tick tock. Was using a iPad Air and latest version of Zwift. Had a look and did not see this listed under known issues. Was annoying as hell,