This is referring to a feature we have in the triple-dot of spam settings "Reset Antispam settings" which when YOU execute that, it will return your defaults to our (new) defaults. Some poor wording on that makes it look like we're gonna reset spam settings on-update, but don't worry we wont reset any spam settings unless you click "reset". We try our best to convert and move settings around if we do end up making changes. Like in DMARC for example we're moving it into the Antispam settings list (with the other checks) but even then, we're looking to see if you already had it enabled or not and just converting it to the new setting.