Oh good!
Yes, sometimes with prolapses, you will see white stuff usually this is urates. It can be watery to a thick gluey material. This usually resolves once the prolapse has healed, ime.
Very Unlikely it's Vent Gleet since she just had a prolapse.
Here's what I wrote for another with similar problems....
https://www.backyardchickens.com/threads/vent-gleet-completely-cement-like-and-impossible-to-remove.1621840/post-27704899
Welcome To BYC
I'm sorry about your hen.
Hard to know if you need to cull her or not. That's up to you, you are there to best access the extent of the damage.
Treating and correcting a prolapse can take time and commitment, so do consider this if you wish to treat her.
Start by giving...