Everyone has a different tolerance to these things.
For me personally, if it's a WG I have seen before and I know she's good, I'd have probably let this slide. At least she did not ghost and tried to reconnect next day.
Sometimes people don't come across the way they intend in messages.
She may have accepted the meeting without really thinking the time would work, or something came up etc. Or just disorganised on the occasion.
Twice in a row like that would be a different matter.