In a recent post someone posted OSCAR results from a Weinmann Prisma Smart machine. According to OSCAR's list of Supported Machines this one is "Well Supported" by OSCAR. Unlike ResMed and Respironics machines that are "Fully Supported". What's the difference between those two levels? Most likely, ...

https://bit.ly/408pTS7
In order to protect patients against Philips’ dangerous breathing machines, Sen. Richard Blumenthal told the FDA and DOJ they must take “the strongest enforcement action possible, including criminal charges, if the allegations are substantiated.”

BUMP

Mine is 12/20.....I average 13 and the highest I get is about 16.5

Have you ever read the explanation of how the Score is calculated. It's on your app. Bring up your nightly score, tap on the seal to see month to date, and then tap on (?).

With the AHI you are showing, your pressures should be increased...not decreased.

Before you try taping, try Xylimelts. They should work well with your FF mask.

As CG indicated, there are several at home tests available for under $200...Aside from the one CG listed, CPAP.COM has one also.
https://www.cpap.com/home-sleep-apnea-test

I keep the machine and mask in the lower drawer of my nightstand

All masks expell CO2 from a small hole beneath the nose. It's not really a leak you can control.

REMOVED

I sleep on my back about 3 hours during the night. My setting is on variable pressure so the machine decides if I need a pressure increase. I have not noticed anything.

Set the hose to AUTO...if that doesn't work, set the hose to manual with a setting of 80 or more.
https://www.youtube.com/watch?v=ctw73sdPU6k

Just a couple thoughts...make sure the air filter is in completely and check the seal in the water tub.. As far as the Vitera, I have been using it for about 2 years. My cushions last me about 6-8 months and I replace the complete mask at about a year. My mask has never made a sound.