Here is the line with the problem:
<?php echo '<img src="' . plugins_url('cf7_spam_prevention/limit.png' , dirname(__FILE__) ) . '" > ';?>
This seems to work:
<?php echo '<img src="' . plugins_url('wpshore-contact-form-7-spam-prevention/limit.png' , dirname(__FILE__) ) . '" > ';?>
https://www.ads-software.com/plugins/wpshore-contact-form-7-spam-prevention/
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