The ‘Rule’ background in IntelliJ is so dark that you can’t read clearly the issue (see attachment). Previous version (IntelliJ 2019.3) was white, it was perfect. I have Material Theme on my IDE (also in v2019.3).
I actually spent a bit of time yesterday investigating this very issue and it seems that sometimes, the underlying component does not use the right text foreground color from the theme.
In my tests, I noticed that it happens more frequently on 2020.1 and 2019.3 than 2019.2, and also affects the rule description panel in the settings.
I’ll try to reproduce with the Material theme to see if the fix I found is stable enough for inclusion in the next release.
Would it be possible for you to try with the latest snapshot of SonarLint?
I did a few checks on my side with several versions and themes, and since the issue is a bit tricky to reproduce, it would give us a bit more confidence about the actual effect of the fix.