This is like, the real 2024 answer.
WotC is attempting to avoid the death yoyo the "right" way by, instead of just punishing martials for getting killed tanking*, rather by making in-combat healing (and spells particularly), more powerful so that it's not just a trap to use them to heal non-downed people in-combat (right now it really is, in most cases).
* = It's very striking that every single thread-starter post I've seen proposing mechanics for dealing with yoyo'ing has been 100% focused on punishing martial characters for getting killed with punishments that will primarily or solely hurt martial characters. Never have I seen it proposed at all that the characters waiting to yoyo heal are doing anything wrong, at all, even though they're obviously "culprits", and if anyone is "exploiting", it's them. Never have I see a thread opened about yoyoing with even a proposed mechanic that would even mess with full casters in a meaningful way. Sometimes as the thread goes on, people propose that kind of thing, but usually the OP rejects or ignores it, because he's only interested in punishing the characters who are essentially the victims here - because they were doing their job, and it got them downed. Whereas the people let them get downed, or even intentionally waited for it? Oh they're fine! I find this misguided behaviour very interesting myself. It's clear that the people wanting this are either genuinely mad with martials (seems unlikely), or, more likely imho, thoughtless proposing what they consider "simulationist" solutions without actually looking at the problem holistically - attempting to cure a symptom, not the problem. WotC I must give some credit to, usually do similar, but here they didn't, I don't know if they've gone far enough, but the changes they made were certainly addressing the root cause more and not just targeting a symptom.
You could make a pretty funny case for applying the exhaustion to the healer attempting to yoyo, rather than the person being yoyo'd too, honestly - say it's "magical feedback" or whatever.