One day passport service - what happens if photo is rejected?

[Interestingpea]

Hi all,
Just looking for some hand holding please 🥲

Just wondering if anyone has used the one day premium passport service before? Where they give you an appointment and you turn up to collect your passport.
I've submitted a photo which was deemed acceptable online but I'm now slightly worried it'll get rejected due to a slight shadow in the background and I'm wondering if they will just ask for a new photo to be sent or give me a completely different appointment slot. Wondering if anyone has any experience with this please? Thanks so much in advance.

They will let you know before your appointment if your photo has been rejected and give you a link to submit a new one.

It happened to my DH a couple of years ago. His photos was rejected for them not believing that it was a recent photo despite us taking our photos and submitting applications on the same day. We just had appointments on different days due to work commitments.