Imam’s ‘awrah (part of body) uncovered during prayer

If someone if in a congregational prayer behind the Imam and sees
the ‘awrah (those parts of the body that a man or a woman must
cover.) uncovered due to an opening in his clothes or due to his
clothes being thin and transparent, then if it is possible he should go
ahead and cover it with something, otherwise he should move and
come out of prayer and inform the Imam by saying “cover your
‘awrah” (in Arabic “ghatti il-‘awrah”), or “protect what has been
uncovered”. He must not stay quiet and continue to pray because it
is known that the Imam’s prayer (in the said condition) is incorrect
and following him is incorrect as well.¹