Thank you for posting and reaching out to the community today! This is correct, it is no longer possible to downgrade out products.
This is due to the significant level of difficulty/complexity of compatibility testing multiple devices with a large number of older firmware versions. We have seen cases where installing older versions of firmware can create unexpected behavior in a product and negatively impact or reduce functionality. Additionally, downgrading firmware in some cases may not only remove newly added fixes or features but sometimes security enhancements or other critical bug fixes.
Can you please let us know what issues you are experiencing with your headset?