Coincidentally, Google's Project Zero published an article detailing
potential exploits in ARM TrustZone software today. In particular, there's an exploit in most Qualcomm implementations and older versions of Trustonic’s Kinibi TEE, which is present in Samsung's Exynos-based phones prior to the Galaxy S8 and S8+.
One interesting thing the article mentions is rollback (downgrade) protection, which is also present in Wii U and has been verified to be present on Switch. The implementation mentioned here is eFuses, whereas Wii U's implementation used SEEPROM.