X is interested in getting more people following lists as a way to increase engagement in the app, and making relevant list discovery better is an important step toward this goal.

On this front, X is now testing a new List display within search results, which will make it easier for users to discover and follow users who regularly post about specific topics.
X is also moving a new "List" category to search results in the web version of the app and images and video will be combined into a single "Media" section.

Tap through on the "List" display and you're shown a collection of related lists, easy to follow by tapping the "+" icon on each.
It could be a good way to encourage list discovery, though whether users actually care about lists is another question, and one that neither the X, nor the previous Twitter team, seem to have a real answer for.

In 2019, Twitter made it an option to pin up to five lists which you could swipe across to from your home feed, making it easier to keep up on topical discussions, in addition to your main stream in the app.
At the time, the team felt that Lists was a largely underappreciated functionality that held lots of potential for expanded use in showing more users more content that they might like.

But list usage never really seemed to catch on, despite the benefits of being able to follow multiple topics in-stream.

Part of the problem, at least from the Twitter team's perspective, is that lists are curated by users and thus not particularly focused as they should be. So Twitter started curating its own lists in a bid to encourage more take-up and changed the name to "Topics", in order to make the process a little clearer.
However, while both of them have the utility degree and have somehow aided in improving discovery, interest in both Lists and Topics has been fairly limited.

Indeed, it has been a long time since the X/Twitter team struggled to maximize interest in the broad range of discussions in the app despite such efforts. Today, the incoming X team is pushing Lists again, in the hopes of boosting topical engagement, but it still seems like a flawed measure, which is unlikely to drive a major boost in engagement in the app.

But possibly, by having better access to a display of relevant Lists, that may help improve discovery at least to some degree.

Really, it’s unlikely to drive much behavioral change, based on what we’ve seen with these past experiments. But X wants to open people’s eyes to the full breadth of discussions available, and right now, Lists is its best bet (especially given that the team responsible for “Topics” is no longer at the company).

Although I think that a better experiment is "Facets", one that the former Twitter team was indeed testing way back 2021.
Facets would allow you to maintain multiple personas for your profile that users could then follow in separate silos. So if users wanted to post about different topics, they wouldn't have to put up with the content with which they had no interest, making it all the more likely they'd participate in various discussions, on various topics, within the app.
I think, for instance, that would impact topical discussion and engagement much more, as it will enable you to join in more discussions without worrying about alienating your main audience with movie or sports takes.

Given that the X team has unleashed almost every other project that the former Twitter team had under testing, it's surprising this hasn't appeared, though there might be more complications to it than it initially seems. This could be because the fact that the creator has to select a topic for each post is probably one, and maybe that extra friction alone was enough to end the experiment.

But I feel it has more scope to alter user behaviors than lists, which have been present in the app since day one and never caught on as a significant usage consideration for most.

Or maybe there's something more to it, but I'm not sure that adding Lists to search is going to be the thing that changes people's approach.