With software update 2019.16.1, Tesla wants to comply with the UN / ECE R79 regulation of the European Union. Those rules determine how driving assistant systems should work in cars. Tesla cars were already approved to comply with that directive, but the company must now make adjustments to it.
The Autopilot is adjusted with the update. This mainly concerns Autosteer, specifically about how far the steering wheel can turn. According to Tesla, this can lead to cars having more trouble with sharp turns. Another change is that the turn signal must now be used before Auto Lane Change can be activated.
Just like other updates, the update is sent over the air. The new software only applies to the Model S and Model X. According to Tesla, the Model 3 complies with the European rules from the introduction.