I think, like all edu-fads that a "flipped classroom" can be done carefully, thoughtfully and incredibly well, or haphazardly and/oras an excuse for shoddiness...
One of our children is starting at a new school shortly who a few years ago changed their whole of school model for 9-12, to what is essentially a flipped classroom model. This isn't why we chose the school, and it's also not the term they use. But what they are doing would be referred to a flipped classroom by many. So far I am overwhelmingly impressed by how organised, and rigorous their set up is. I think my child is LESS likely to get lost in the cracks, and that if we get locked down yet again, that their system will work far better for her than her previous school.
There is much more chance of success when adopting any new model when it's every teacher, ever class, and supported by extensive (high quality) planning, training & infrastructure.
So my concerns about your situation are not the mention of "flipped classroom" but rather: Why is the teacher not teaching if they aren't sick and on sick leave? Why are you getting the impression that they aren't interested in actually teaching? Why are they introducing a new model on their own just for one class (or for all of their classes? but not as a whole of school lead method)?
These are crazy and stressful times. You sound stressed, understandably. Is something going on with this teacher that is reducing their capacity to be their best self? Beyond the blazingly obvious...
