The daily salt only protects hashes written after it shipped. The ones already stored had been computed with a fixed value from the source code, so they could still be traced back to a visitor's address by someone with read access to the table.

On the first start after this release the API rewrites every older visitor hash, in analytics events and form submissions, with a value derived from a random key that is deleted when the job finishes. It runs in small batches in the background, so the API stays available while it works.

Your numbers do not change: the same visitor still has the same identifier within a day, across analytics and forms, so unique-visitor counts and funnels read the same before and after. The one exception is the day of the release, when a visitor seen both before and after the first start can count twice.