want to change author image in the backend, Comments

any help???

I am getting same in other website. Having same issue. I used same plugin here one User Avatar.
see Users at backend https://www.screencast.com/t/J96kjqHq
Comments at backend https://www.screencast.com/t/wAsr7bAeBBXI
Even there is no Frontend changed profile image https://www.screencast.com/t/xsFmOBgH

I am currently researching this and will get back to you.

sure

any update???

This snippet should fix the issue for you:

add_filter( 'get_comment', function( $_comment ) {
	if ( ! empty( $_comment->user_id ) && ! empty( $_comment->comment_author_email ) ) {
		$user = get_user_by( 'email', $_comment->comment_author_email );

		if ( $user instanceof WP_User ) {
			$_comment->user_id = $user->ID;
		}

	}

	return $_comment;
} );

I’m not going to add it to the plugin because doing so would have various unintended consquences.

Alternatively, you could go into the database and manually update the user_id field in the wp_comments table every time someone adds a comment. You can just set it to 0 and then the avatar will be retrieved using the email address.

I will try it today and let you know. It works or not.