On my morning commute I burped my rear tire twice having never had that issue before. The rim is a wtb i23 (taped from factory and rate "tubeless ready") and it has a Wtb Riddler tire mounted (also "tubeless ready"). I've had the tubeless setup a bit less than a year with no issues to date, though I haven't ridden the bike in a few weeks. With my laptop etc I was a bit heavier than usual but I've never run into this before on my gravel bike.
First time I was going up a curb and turning (resulting in a sharp off-camber situation). The second time was similar (also a sharp turn) but I didn't lose as much air. The valve is fine so I assume it was a true burp (air out of tire bead).
Is this just a case of not running enough pressure?
I'll top up my tubeless sealant tonight, check the bead and the trueness of the wheel (just trued it, but who knows).