The following changes were introduced in January, 2020.

We are planning to update all Matomo instances in the following days. Updates will not affect your tracking.

In the new release (3.13.1) the focus was on:
▪ fixing a few bugs
▪ fixing a regression in tracking unique visitors affecting some users
▪ making Matomo tracking slightly faster
▪ and ensuring compatibility with the upcoming Chrome 80 browser.

Chrome 80 is planning to make all cookies that don’t have an explicit SameSite option have SameSite=Lax by default. So far it has been an optional flag but Chrome 80 (release due in February 2020) will have it enabled by default. Matomo 3.13.1 will be fully compatible and won’t issue a browser console warning anymore.