I'd say it's 100% the move. They definitely pick upon change even at a few months old.
Honestly rather than wiwo, I think you'd be better staying with her until she sleeps during the transition to the new place and then after a couple of weeks then look at gradual withdrawal. 21mo is pretty big on Separation Anxiety so she could actually fear she will be left behind when she is left alone at bedtime, so hard as it is for the time it takes to be there,that's 100%what she needs, rather than a routine tweak.
From about 18mo, routine issues are more often shown with o early wakeup and stalling issues and bedtime tears and problems more emotional issues or very overtired, but looking at your routine, being really overtired seems less likely.