I find the link colours in posts (questions and answers) quite similar to the colour of regular text -- to the point that I'm not sure if I can tell if there is a link in the text at all.
Could the colours of the links be changed to make them stand out more?
This was mentioned under the discussion on the new theme (at least by Kusalananda, some others seemed to agree too), but in my eyes, it was an issue on unix.SE even before the new theme. The new theme just made it sufficiently worse that I actually bothered to write this.
There are other sites that seem to be using the new theme, but which have better colors on the links (I looked at math.SE and askubuntu), so it's not related to the new theme, and this is better placed as a discussion of its own.
Kusalananda also asked about changing the colors locally, on client-side. That would of course do as a workaround for the issue, but I think it's bad enough that it should be fixed site-wide.
I don't really have an opinion on underlining or such decorations. Of course that would make the links stand out quite obviously, but maybe it'd be considered distracting.
Screenshots to clarify what I mean
(I put the pics in quote blocks so they don't get mixed with the text of this question. The gray boxes come from that. I also get a dotted underline under the pics, since they're links to imgur, and on meta, links seem to be dotted-underlined.)
From math.SE, this is quite noticeable:
From Askubuntu, again, quite noticeable:
From unix.SE, almost invisible, though there's context here that hints at the presence of a link:
Again, from unix.SE. This is almost invisible. There is a link in one of the words.
(Screenshots are from Chrome on a Mac. I shouldn't have any local stylesheet modifications or such.)