With extremely weird (from a rules perspective) effects like this I’d always suggest not having it be a feat. If you want something like this for narrative reasons then you can grant it as a GM, if for example it’s just part of how your world works, Dark Souls style.
The reason I say to not have it be a feat is that if you open it up to all players then it either becomes something everyone wants (at which point you may as well have just given it to everyone anyway) or it becomes a bad investment of feat points (making the one or two players who get it feel like they’ve wasted their levels).
From a gameplay perspective, I don’t like the “losing xp” part of it. If a character has this feat and dies once, they’re more likely to die a second time because they’re lower level than the rest of the party, which then makes them more likely to die a third time and so on. It also requires players to spend a lot of time choosing what attribute points and feats they lose. All in all, it just seems like it would feel bad for the players; if I was a level 6 player that had this feat and died, I’d be 3 levels below the rest of my party and I’d strongly consider just making a new character.
For a suggested improvement, taking all that into account:
For the duration of this campaign, no player character can die. If your body gets destroyed, you live on in what’s left of the body until your full body resurrects, 48 hours later. Once per day another character can attempt to heal you, removing hours from the resurrection timer equal to the healing rolled.