QR code sticker - what's it all about?

When I|D bike, the manufacturer, was asked about the P178 sensor, the answer was as follows: 

Originally, our TMM4 sensors never had any visible protection. Our conformal coating is so robust and durable that it can easily withstand various types of continuous salt spray tests (24/7 underwater) for more than 3 weeks. Furthermore, in the more than 12 years of TMM4 history, we have seen sensors packed with grease, oil, dirt, sand and other stuff, and generally this has never affected the function of the sensor. Still, OEM customers and dealers kept asking the same question: "Do we need protection?" It seemed like we weren't able to get our message across. When we finally started implementing the QR code years ago, we decided to combine the two things: 1. the sticker on the back is the carrier of the QR code and 2. it can stop the demand for some kind of visible protection.

Jan Goes / I|D bike - 2020

The adhesive is therefore not necessary from a technical point of view. In practice, it comes off quite frequently. Alternatively, after thoroughly cleaning the plate, you can replace the adhesive with a simple, black electrician's insulating tape. Make sure that 3-4 mm around the thru-axle thread is not taped (freewheel support).

The QR code adhesive code only contains an article designation. As a spare part it is
for the ST5 2018 | ST3 | ST2 6V | ST2 S 6V | ST1 X 6V here available.

Alternative

With the introduction of new models (P178, P211, P218), the TMM sensor has been continuously improved. In addition to mechanical changes (slot width, mounting points), the sensor has also become even better protected against dirt and water (IP 66).

As an alternative, I had "protected" the former P178 sensor on my ST3 with electrician's tape. This worked, but did not improve the somewhat erratic behavior. With the P211 / P218 at the latest, this DIY method is obsolete.

On the Website I|D Bike writes the following about the newer model (for Stromer P211/P218):