Hi Pedro, were you able to find the source of the image you want to replace? For example "images/@servicenow/now-illustration/no-search-results-lg.svg"
Once you have that, you need to have a SVG on hand to replace, in my case I was provided with a simple PNG image so I found a PNG to SVG web tool by searching on the web.
Once you have your SVG, you can go to System UI > Images, then create a new record and in the name, put the path of the file (for example: images/@servicenow/now-illustration/no-search-results-lg.svg), then upload the file to the record and save.
The images are cached in browser, so you will have to clear your browser cache or test in Incognito. If your user have never used the AI search in production then it's not an issue but if they have, then they will have cache issue. Typically ServiceNow does something to clear that cache when you install a patch, I'm not sure if it applies here.
