While using reading glasses when accessing the Discourse website, in dark mode I find the coloration of the Solution banner very bright. Also the single line pre formatted text has a very bright background in the default settings of the Interface. In combination of the red colored text it is disturbing when reading such formatted content.
To illustrate, I will create a solution for this topic and create a dummy text to give an idea of how it looks like.
There are alternative settings, with a “use at your own risk” comment:
It looks this way, which is much better:
However to distinguish better on of the other i would prefere a more balanced coloration… as an example I would like to propose something like this:
I am looking forward for comments from users in same situation, which share the pain of wearing glasses.
This is a Dummy text. This is a Dummy text. This is a Dummy text.
While the block of pre formatted text bock looks much more relaxing to read:
This is a Dummy text. This is a Dummy text. This is a Dummy text.
This is a Dummy text. This is a Dummy text. This is a Dummy text.
In Light mode it looks like this for me.
I have to admit in Dark mode it is a tad bright 
Wild guess; this can probably be changed by an admin via the theme CSS.
Not sure why red was chosen for code blocks. Might be worthwhile looking at the stylesheets for the theme too.
I like the colours, but if it is causing discomfort, I would be fine with having them muted.
Actually getting that changed might not be straightforward though…
It depends on what is decided that needs changing.
Whether it is inline code, code blocks/preformatted text or using text to disable highlighting (site-wide).
Meta Discourse has topics describing how that can be done.
Can be applied from here:
Admin > Customize > Themes
Needs some CSS tweaking.
To be clear, I have no issue with the colouring but I can imagine for some people it might be a bother.
I do not mean that it is technically difficult, it is as you say something that caan easily be looked up.
The difficulty is in making decisions and having admin execute those decisions.
