After updating to WordPress 5.5 I had a number of problems which jQuery Migrate "fixed". But I dug deeper and found lots of problems when the only activated plugins were Gutenberg 8.7.1 and Yoast SEO. I then discovered the WordPress core bugs that had been raised, and for which a fix was being developed. After applying the fix I noted I didn't actually need the jQuery Migrate Helper. Perhaps others have had similar experiences to those I documented here: https://herbmiller.me/how-to-survive-wordpress-5-5s-removal-of-jquery-migrate/