This looks like a repeater, are you using the user ID in the if and while part of the repeater call?
Is the field set to return an array or URL?
But I think the issue is this:
<img src="<?php echo esc_attr($nomInfo['user_avatar']); ?>" alt="author-avatar" />
Should be this:
<img src="<?php echo esc_url($nomInfo['url']); ?>" alt="<?php echo esc_attr($nomInfo['alt']); ?>" />
