Been running somewhat similar combo few months and toy'd around with taking the screenshots of the selectors axe-core/playwright reports as I didn't notice such feature in neither playwright or its html reporter. Do you happen to know if slack patched this or is this feature available somehow ?
And if you are willing to answer some other questions regarding axe-core itself, I might have few.
Screenshots of issues is something we support in many of our paid offerings, but not in axe-core itself. It sounds like the Slack folks implemented their own version of it.
And if you are willing to answer some other questions regarding axe-core itself, I might have few.