The selected namespaces are listed as a set of pills underneath the namespace preset selection. Tabbing through them gives not much context or information on what they mean or how they can be interacted with.
Suggested improvements (see what was done in T342245: Screenreader support: When focusing expandable panes, the pills are read out but no context is given):
- Make the Advanced search: label semantically more explicit https://gerrit.wikimedia.org/r/c/mediawiki/extensions/AdvancedSearch/+/954603/
- Convert the "list" of search term tags into a real html list https://gerrit.wikimedia.org/r/969297
- Add a descriptive title to the list that can be read by a screen reader https://gerrit.wikimedia.org/r/969297