Please add https://meow.social to the valid Mastodon URL field.
Note: Luke, I do hope you can find a way to automatically vet verified Mastodon instances so that we don't have to keep submitting a feedback post if/when we need to add our preferred Mastodon instance. Mastodon is not like Twitter or Facebook where there is only one domain hosting an instance... Mastodon (more well known as only a small part of the wider Fediverse) is more akin to how email addresses work and has many different host domains. So, if more people opt to use Mastodon, there will be a LOT more instances to approve as valid URLs for that field.