After they managed to somehow squeeze in the pitch, I stopped worrying. All minor issues from then on. It will be fine.Not sure what the black is, possibly some of the anti-slip paint that has been spilt. Some of the screed looks to have blown at the bottom of the steps though.
Ultimately all of these issues will be sorted. LoR will have a minimum 12 month defects correction period, plus there will be warranties against anything and everything.
It's a £750-£850m project. There will be issues and things that need correcting. Nothing to worry about.