Open Caption, text background opacity Issues

[bertp5625049]

I'm using the latest Premiere Pro version 14.3.0 (build 38), using Open Caption with 75%  background color. The timeline preview looks find, but when I render with Media Encoder, using Burn in Subs into the video the background behind the text flickers to lighter colors. I ensured all captions uses the same setting but this happens to a few lines of captions. Anyone know why?

Below are the flickers of the background color.

[Mike Dziennik]

Do they look ok if you render them on the timeline in Premiere? If so, you could 'Use Previews' when you export as a workaround.