Is this a thing?
Yes it is a thing.
We had sleep disturbance every half birthday but it would be probably a month or a few weeks running up to it and then beyond too. Actually only this year we seem to have skipped it but I think that's because he is 7 years old and the stages of equilibrium and disequilibrium spread much further when they are this age (although he has just recently decided he can ignore his morning lights which is his cue he's allowed up).
Lots of kids are dropping their nap at this age though so it can be that too, it's likely that continuing a 2hr nap is impacting on nights and then because she's tired you let her have another 2hr nap. It could help to reduce the nap time quite significantly, perhaps do it in stages of 15 min per day moving the nap later but ending it at the same time?
Mine didn't do well with a capped nap to be honest but most LOs seem to do well with it. Mine was doing 2hr nap at 2.5yo and a month later dropped his nap cold turkey, gone, just like that. Nights went longer.
During our half birthday regressions I generally shifted my DS's BT much later so we just didn't have the hour long battle at BT, he needed the sleep we all knew that but it was pointless going through the battle. Once he was through the regression I shifted BT back to normal and his nights lengthened again.