This is one of the many new features they’ve been trying from what I can tell.
I recall “testing” out the free20% HP increase for one mission a few weeks back. Enjoy it while you can, first time reporting it, I never saw it much again after.
(I do at times see it on puffin, although it’s only there and limited).
Edit: to explain the 20% hp thing, before a mission, you could “watch” an ad for the 20% and you’d get it right after (2 seconds y/n ad, either option gives you it). This looks like a loot version of that one, seems neat. But I doubt they’d make a epic/leg one. Unless this isn’t going to be limited.