If you see an orange line on your History Center chart with the label "Puppeteer Browser Service changed", it means that Monsido has started scanning your domain with a new generation browser service technology called "Puppeteer".
A browser service is an automatic tool that Monsido uses to render and crawl your website. It provides the basis for finding issues on your website and reporting them to you through the Monsido UI.
With the new generation browser service, Monsido is able to provide more accurate crawl results, even for websites that have a very complex structure. This also means that we may find more issues on your domain than when we were scanning with the previous browser service. In other words, you may be seeing a slight jump in issue count as a result of moving to the new browser service.