It has been proven possible with such a mask but with inconsistent result. Those mask doesn't provide a 100% air seal since its main function is to add oxygen and not really keeping it out. Even if you could keep a good seal involuntarily reflexes when unconscious could compromise the seal very easily. Talking from experience, just having a beard while using a full face mask allowed me to breath quite easily from an airtight source. Even a small and seemingly insignificant leak is enough to sabotage the attempt.
Because of these reasons it's not recommended to use these cheaply made mask, pph advice against it and most of this forum will agree.
There have been a test using a very similar mask, I don't have to source left but I have a picture of the results. One of the subjects didn't have a good enough air seal and as a result it took much longer time until ctb. They concluded the mask is not good for this purpose.
It's unfortunate that rumors spread of bad practices that could potentially damage people for life.
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