I think we're going to need a software update for this, so I hope the (Netflix?) devs are reading. When watching Netflix HDR content (example: Altered Carbon), the captions are very dim compared to non-HDR (example: Riverdale). Obviously, the brightness of the captions need to be "elevated" when in HDR-land. In fact, since HDR has such range, Netflix should probably have an opacity choice for text. 100% should be jumping off the screen (full brightness). Note: I don't like to use any background on my captions. I like for them to be as non-intrusive as possible while still being easy to read.
Also note, my Sony X900F Netflix built-in app does not have this problem.
However, if a solution already exists, I'm all eyes/ears.
PS I know this is a Roku forum, butttt, Netflix app devs: PLEASE put caption settings in the Netflix app (or scrape them from the Roku caption settings). It's a pain in the neck to experiment with caption settings by changing them on the website, full exit from Netflix Roku app, re-entry into Netflix, test play a stream.