I am trying your method but it is outputting the same unique ID per repeater row and not a unique ID ?
<div class="accordian">
<?php
$uniqueid = uniqid('question');
$count = 0;
while ( have_rows( 'layout_nine_questions' ) ) : the_row(); ?>
<div class="accordian_single">
<input type="checkbox" id="<?php echo esc_attr( $uniqueid ); ?>">
<label class="accordian-label" for="<?php echo esc_attr( $uniqueid ); ?>"><?php the_sub_field( 'layout_nine_question' ); ?></label>
<div class="accordian-content">
<?php the_sub_field( 'layout_nine_answer' ); ?>
</div>
</div>
<?php $count ++; ?>
<?php endwhile; ?>
<?php else : ?>
<?php // no rows found ?>
<?php endif; ?>
</div>
</div>
