I had the same question but more global purpose than the topic you asked about…
Reff Pixels said it has no license applied and that it is up to our best judgement for proper legal usage… Based on the fact that it isn’t against the law to put icons and logos from other companies on your own website/apps as long as you don’t attempt to fraudulently claim ownership of the other company’s icons and logos you use… That’s pretty much what “Use at your own discretion” would imply in overly simplified terms – So use common sense and be reasonable and think before you do something with them is a smart way to handle this task. Shouldn’t be too difficult to do for any intelligent and reasonable developer.😅
I mean, it is pretty common for developers to use the icons for other companies’ products and services in their apps especially in situations where there’s file/link sharing like with social media sharing features. So that’s a pretty good example of a proper use case for these icons.