error causes PHP process hang

Block Editor hangs – keep getting page unresponsive. Hosting provider found hung PHP process and errors, per chat excerpt below:

Thanks for waiting, the only thing I found regarding a plugin was this:

PHP Warning: foreach() argument must be of type array|object, null given in (directory string removed) /wp-content/plugins/modern-footnotes/modern-footnotes.php on line 382
Warning: foreach() argument must be of type array|object, null given in (directory string removed) /wp-content/plugins/modern-footnotes/modern-footnotes.php on line 382

Other than that there is no indication of another plugin that could have affected the site