Any exercise depends on the execution and goal.
At one time “full sit ups” were “in” , I did them in P.E. as a kid.
The “roll up” in Pilates is used all the time which is very similar to full situps.
I think any exercise done “just because it’s out there” and without guidance can be contraindicated.
As always, know your reasons why, keep your certification and CEC’s current, keep learning, keep asking questions, and most importantly, learn the biomechanics of all the exercises and then decide what works best for your clients.
Check out your ACE guidelines for this.