Wrist detect and hiking pause issues on Apple Watch Series 11 with wrist tattoos

Yes. That's been a problem since the very first Watch. It's not restricted to the Watch either. The same type of problems are present on other smart watches that use optical sensors on the wrist.

If you purchased it less that 2 weeks ago, return it for a refund. it is not going to work well for you.

Skin pigmentation as well as tattoos can affect pulse oximetry and related sensors, yes.

Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis

• https://pmc.ncbi.nlm.nih.gov/articles/PMC9102088/

A review of the effect of skin pigmentation on pulse oximeter accuracy

• https://pmc.ncbi.nlm.nih.gov/articles/PMC10391744/

Easier to read:

• https://www.theverge.com/23567992/wearable-tech-tattoos-fitness-tracking-how-to

Emergency Medical Services (EMS) classes cover this topic, as well as other sensor errors that can arise.

Tattoos under the sensors of the watch have been an issue in the past, not only effecting Apple Watches.

The light emitted by the sensors can not be received as expected and the wrist detection is not working correctly. The ink of the tattoos seems to be the problem.

Also, Apple may have fine tuned the sensors again to support new features like hypertension notifications, which checks the blood vessels.