It is pressurizing on output due to the flow through the device, the same thing causes some underpressure when breathing in.
But I doubt it is enough to draw a vacuum strong enough to break adhesion. Still, better safe than sorry, it would be good to read the instruction manual of a professional unit to see what kind of failure modes they have listed there.
I read a lot of stuff back in 2020 because I was going to be coding up controls for an emergency ventilator... you would not believe just how little pressure difference it takes to permanently ruin your lungs... less than 1 PSI if I recall correctly.
You really don't want to over-pressure your lungs with 1 PSI, that's huge for tissue. For a regular party balloon that you blow up the pressure is less than 0.5 psi. But a flow meter in a sports measurement device should be a fraction of that, after all, the back pressure is going to take away effort that should go into providing work.
