Sometimes, regression is simply due to distraction, or an unwillingness to give up a toy or activity. Your child might be waiting until the last minute to go and doesn’t make it to the bathroom in time. Many children don’t want to take a break from playing to go to the bathroom.
She’s still young.
It can help to back off a little
Stay calm
Do not punish
Lots of praises for any success
She’s dry in the night ? That’s awesome, tell her every morning; so good, I’m proud of you !
When you suspect it has a physical cause, it may be good to visit the GP

Just one of those things you gotta wait out patiently to happen on its own. The more its a big deal the harder it will be and longer it will take.

Your daughter could have a kidney problem, which means she may be passing very little urine and won’t feel as though she needs to. If she is close to kidney failure she will make very little urine. I would seek an urgent Doctor’s appt.
She could have an urinary tract infection and may be putting off going if she is getting a burning sensation. A few years ago I had a UTI with no classic symptoms. It was diagnosed after persistent vomitting over a few hours, then a spike in temperature.