Miles
This is very clearly not the case as per Google:
https://store.google.com/intl/en_in/ideas/articles/google-tensor-pixel-smartphone/
With the new Google Tensor G5 chip, your Pixel is designed with even stronger security from the ground up, helping to protect your phone throughout its entire life – from manufacturing and shipping to when it’s in your hands16. The security of critical systems has been enhanced, including the digital "keys" that safeguard your personal data, making it even harder for someone to tamper with your device.
The footnote clarifies that it is a direct comparison with the Tensor G4, so there should be generational improvements.
Now the impact/relevance of the improvements they tease is debatable since the Titan M2 seems to be the same silicon but just like the introduction of MTE with the Tensor G3 was not strictly tied to the Titan they could be potentially very impactful.
They seem to imply something has changed in regards with the Security co processor inside the SoC/Trusty.Maybe even the modem/radio/baseband altho that is purely speculation on my part.
We will just need to wait until the actual hw is in the hands of competent people with the required expertise to make an informed assessment.