Google released Android Q Beta 4 on June 5, but soon after, the company halted the rollout following reports of failed installations from many Pixel users. Well, the issue has been resolved now as the rollout of Android Q Beta 4 has resumed.
All the devices that are already enrolled in the Beta program, including those running the previous Beta 4 build, will receive a new firmware over-the-air bearing version number QPP4.190502.019.
The new firmware weighs around 300kb if you are already running the previous Beta 4 build, but if you aren't, then you should expect to receive a much larger update.
Furthermore, if you can't wait for the OTA to arrive on your device, you can install it manually by flashing the system images which can be grabbed from here.