I wanted to bring a new concept to the floor- sometimes kids who are off the derech, might not be doing goyish tendancies, but doing the tendancies of other sects of judasim.
I personally have become more frum while my family is modern orthodox, and to them I am the crazy one so to speak “OTD” from how I grew up. While to me this is def not OTD, i understand what it is like for any parent from any level of observance to see their kid become different.
coming from the other perspective, although when your children go off, it is scary and unknown, if they are only doing MO tendancies, although your rabbi/family hashkafa is different, keep embracing your child, because hopefully they will come to realize that lifestyle is not for them. and if it is, as long as you put in the effort to make them love yiddishkeit, maybe the learning lifstyle, or the pressures were too much for them. and maybe its a good time for each of us to introspect and see if we were pushing our kids too much in a certain direction and not catching the red flags that it was too much for them! Hatzlacha and ksiva vechasima tova!