Friday she had dozed off in the car with my parents for 2 min and Ben had a train wreck nap. Slept fine at night but Saturday is when the 5 am wake ups started
That car nap then not having a proper nap could easily explain the following morning EW and even taking a few days to get back on track for a some LOs. When my DS was around 5.5yo we had a day trip and got stuck in traffic, unavoidable delay, he napped on me on a bus and train because it was getting near BT. In the end BT was only about an hour or so late I think and he'd had that sleep on me, but the night was horrific. Multiple night wakings screaming with OT many times and wet the bed, he had been dry at night for 3 years by that point! So I would say, yes, one day can de-rail but equally you can get them back on track too. And you will!
I would just stick to your routine help her sleep if needed.
Sounds like your LO wants to potty train or at least practice and work towards it. Sometimes these skill developments can cause disturbance to sleep.
I'm not sure I understood your post correctly, it looks like she is waking in the early hours saying she needs to wee and still has a dry diaper, is that right? If so I would put the EW down to developmental reasons. Had the same here and if I took DS to the bathroom it was bright sun so no going back to sleep afterwards but i put a potty in his room so we could treat as a NW, wee in the dark with minimal chat, just a little whisper "I are you finished? OK back to bed, night night" and he'd go back to bed sometimes he didn't sleep but stayed quiet, sometimes he went back to sleep.
Maybe offering the potty before BT could help? And before nap time?
There are lots of LOs this age ready to PT.