Could be but then again it was a telephonic round with a shared coderpad, i couldn't even share my screen to begin with so creating diagrams was out of the picture.

Well, debugging questions are not the best solution to interviewing either since a couple weeks later i had a 'debugging' round with Freshworks and i could easily debug that code piece in given time.

What i've always preferred for interviewing are take home assignments, that generally helps figure out OOD/LLD skills that will be required from you at the job.

Although, all of this is subjective to a person's opinion.