Her heal can only be triggered twice before action not infinite, so if you used mystery that turn she will use first charge there and won't have another one for second auto attack.

Yep you're right. Makes sense now, thanks for the help! A mod can close this thread.

This happens also if you use other ninjas that grant a second standard attack like bee sst or kurotsuchi, the point is that sakura is just now way op, if you give her also an unlimited number of times to use her passive would be way too op.