Thank you very much for the details, I was able to find the issue in the configuration.
You had the 'Search in pages” option enabled, so I turned it off: https://i.imgur.com/sfx35B5.png
…and some of the taxonomy terms set as results as well, I turned them off as well: https://i.imgur.com/kq9DRZt.png
I have disabled them, now it will only display the publications as results.Best,
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