I'd call 111 and ask advice from medical professionals
This can be a sign of an allergy too, this is when the drs started listening to me about suspected allergies with my daughter. If you've started weaning write down everything you have given in case it happens again, it'll be easier to trace back.
My baby had a few instances of that type of thing, could be constipation with straining or something to do with the membranes. My little ones one only happened twice and he's okay, but if your worried get it checked.
My son had this and he ended up with an allergy to the protein in dairy! If you ever find like black tar like stuff in poo it means that there would be a bleed in the stomach or above and would need urgent medical assistance, this on the other hand keep this picture and ring your GP or midwife and consult with them with next steps and don’t worry, she could’ve done it from baring down and pushing if she has been constipated, my youngest baby had this from being constipated xx
I’d consult but not panic. If the blood is red, means it’sfresh and must be from after digestion. Maybe a small tear from straining. Less worrisome that if it was black in the stool (then that’d be a sign of internal bleeding)