The biggest issue is that the attestation hardware and the application client is the same device with the same manufacturer, who also happens to have a slight conflict of interest between monetizing customers and preserving any sort of privacy.
IMHO the pro-attestation forces are so overwhelming that we should all cherish the moment while we have anything open left.
That seems completely contrary to the spirit of EU laws and regulations, which tend to be about protecting the consumer, preventing monopolies, ensuring people can generally live their lives where all things that are mandatory are owned and ran by the state and foster a certain degree of EU independence, with a recent focus on "digital sovereignty".
This one is a five for one against all of those goals? Harms the customer (you could see this as the polar opposite of GDPR), strengthens entrenched monopolies, force citizens to be serfs of one of two private corporations in order to access information, and on top of that, like it wasn't enough, willingly capitulates to the US as the arbitrates of who is a valid person or not.
This is so against the spirit of the EU itself that it would almost be funny if people weren't serious.
Europe's dependence on American tech is a major pain point but realistically, there are only two smartphone vendors. If a European vendor does rise up, I'm sure whatever app comes out of this process will happily hook into the hardware attestation API for that OS as well.