The last few nights, I have woken up repeatedly, unable to breath. There is no apparent cause for this. The vent holes appear to be working, plus there is some leakage in other parts of the mask, but not significant, that would prevent CO2 buildup. I last washed this mask using Dawn Dishwashing detergent. It's been used maybe 20 times. My data doesn't show a bunch of events. In fact, I don't even get RERAs with this mask (AHI is usually under .6).
I use this nasal mask when my nose gets sore from pillows. At the time, I didn't know you couldn't replace the nose parts, so I just use it as a backup because I can't afford to replace the whole thing regularly. It's a comfy mask, and I get no significant leaking from it, but it does leak more than pillows. Tonight, I'm going back to my pillows (nose healed up), but need to resolve this for the next time. In fact, I had to switch to the pillows partway through the night last night after waking up twice with this issue.