In the latest entry to his Discoverability blog, Simon Carless discusses the Steam refund rate as a potentially significant metric.
The refund rate, which, according to Carless, averages 8-9%, can be as high as 20%. If yours is above average, you might want to dig into the refund comments that Steam requires users to leave, no matter how depressing those might be. This could be a way to identify some recurring aspects of your game that people are frustrated with.
Specifically, the analyst points out technical support issues. Apparently, users are somewhat more likely to bring those up in refund requests, rather than in reviews or via dedicated Discord channels.
Even if your refund rate is within the average range, you can still glean insights from reading the refund messages.
The refund data is available on Steamworks Sales & Activations site. You should click on Steam Packages and go to the Refund Data link on the right.