Whenever a child is on the cusp of an age change, and typically at 2 years old... sleep tweaks, happens.
They child is changing SOOO much, developmentally and emotionally and per overall development.
It is, growing-pains.
It is a phase and temporary.
Just try and keep to the usual sleep routines and bedtimes and nap times.
A child this age, still needs to nap.
And yes, they also get separation-anxiety too. This occurs at various age-stages and is manifested differently, per age.
Your child is over-tired.
She needs to nap.
Getting her to nap or sleep... even if you need to co-sleep with her until she falls asleep, may be needed.
Kids also get more needy, when they don't feel good.
Or when yes, there is a lot going on in their lives.
Just soothe her as need be.
Talk with her etc.
Also at this age, they start to get either "Night-Terrors" or Nightmares, and various "fears" of night time. These are developmental based.
LOTS going on, at this age, both developmentally and emotionally for a child.
Emotions are not even fully developed yet, at this age.
Just help soothe her.
It is a phase.
For us, we have a floor futon in our room. IF/when our kids need to, they can go and sleep there or when they are sick.
It is no big deal. It works for us.
Next: when a child is over-tired or has sleep deprivation... they are not themselves and it actually makes it HARDER for them to fall asleep and they wake, more.
Even adults, are not themselves when they are sleep-deprived.