I usually make a huge render region and and retouch it out.
I have no idea where these would come from. Do you have some emissives in the scene?
No. I always run into this prob when using California desert hdri.
This is an old HDRI from the HyperShot days. Back then we doctored the HDRI by putting a bright 8 pixel circle in the middle of the sun to increase the intensity of the light source. Maybe you can manipulate the HDRI in the editor by dimming the sun light a bit.
Did you change some brightness/contrast settings?