Air bubbles forming in/expelling from mouth

Air bubbles forming in cheeks, expelling from mouth constantly throughout the night.... making me nuts. I've used a machine successfully for 15 years. At age 65, I've started having issues. Mask is Swift LT nasal pillows, also used this whole time (replaced periodically). I have slept soundly for YEARS with this system and am both psychologically and physically dependent upon the machine. For that last two months or so, I've had this issue of constant air bubbles forming in the mouth and then expelling from mouth, making it very difficult to fall asleep or stay asleep. Friend thought pressure was too high. Changes to pressure (and every other setting I could think of) did not resolve or positively affect the problem.
Things I've wondered: you know how old people have a lot of laxity in their necks, drooping jowls, etc? Well, I'm getting some of that. Could this be an issue? Old people loose muscle tone in general... should I do tongue exercises to try to keep tongue near roof of mouth during sleep? I imagine I may need to try to use a full face mask. I'm loathe to do it. I love my nasal pillows. In praise of nasal pillows: My 65 year old classmate from high school JUST had to go on cpap for apnea diagnosis and uncontrolled blood pressure. NONE of the newer model masks worked for her. This older model mask, she can actually USE. She gets a good seal, mouth stays closed, AHI low, etc. She is thrilled . Was loosing hope.

If anyone has any thoughts on therapy settings or other ideas, please let me know. I'm feeling quite desperate (probably from lack of sleep). I lay in bed for 12 hours with the mask, maybe sleep 7 of those hours. I swear I'm about panicky just thinking about it. I miss my good sleep.

I use mouth tape each night to keep my mouth closed. See this video.

Mouth Taping for a Better Sleep

Most people can get away with a 1" wide strip of 3M gentle paper tape. I use that plus a wider strip of Mefix tape. The 1" 3M alone does not seem to be enough to keep my mouth closed. I also am very adverse to using a full face mask. I use the P10 make with the Swift headgear.

I think I may have resolved the problem, by about 90% anyway. I began with the assumption that the air bubbles were forming in mouth because airway was collapsing, thus collecting air in the mouth cavity. I turned off ALL settings that cause variations in the pressure while breathing, notably AUTO and FLEX. I then cranked the pressure up HIGH... to 11.5, as an experiment. The higher pressure, without variation, seemed to keep the airway open consistently. Still had a few air bubbles, but it was tolerable. Had a good night's sleep and very relieved.