Russian 'Prisoners of War' Voice Disquiet – 'Shame over War in Ukraine'

Not in and of itself. Article 13 says that they must be protected against "public curiosity". Article 14 says they are "entitled in all circumstances to respect for their persons and their honour".

That's generally interpreted to mean that if they're voluntarily and sincerely making these statements, then it's OK. But since we can't be 100% certain of that, it's always going to raise red flags.