I've not been offered the option to NOT run Windows 11. I had a windows 10 installation, in the Dev Channel.
Microsoft did not allow choosing (and does not allow returning back) even if this required update has removed almost all security that were in Windows 10 (official release) and in the Win10 Dev channel as well (that stopped working: TPM2, VBS, HVCI, DMA protection, MDAG, CG, DG)...
The hypervisor is still there, but with severe degradation (including the drop of graphics acceleration, ans enhanced sessions in VMs)
And even though TPM2 is still detected, and reported as active, ready, and has all keys loaded, including for hardware assesment and driver verification), it still spams the Event long every second with failures: from what I see, it attempts to update an SHA1-based hash, while the TPM2 is configured for SHA2 and Windows 11 does not even support SHA1 (the TPM2 module supports BOTH kinds of PCR registers, windows11 uses the wrong set, just because it uses the first supported algorithm reported as being available).
This is definitely a bug of the TPM implementaiton in Win11, not respecting its specifications.
If you have a TPM2 chip it MUST support SHA2, and can still support OSes using TPM1 with SHA1 PCR registers (that cannotbe disabled by the BIOS UEFI preboot before you've selected the OS to boot on). The bug must then be in the Windows 11 EFI preboot image (that runs even before entering the UEFI BIOS or selecting the OS to boot on from the configured BCD store)
May be there's a missing setting to add into BCD to ask the preloader to use SHA2 and not SHA1 even if it is reported as being available and ready as well. But I don't know such setting, and this shnould not even be needed: "tpmtool" for example correctly enumerates the PCR registers in both banks (SHA1 and SHA2), and they are correctly prepared as they should be.
I have also run the latest version of the Microsoft ADK tool for hardware assesment (version still made for windows 10 withjout anything changed for Windows 11), and there's no error at all: this means that the "Ready for windows 11" certification jsut does not exist, and the new requirements made by Microsoft were never tested (not even by manufacturers, except by some secret private channels)
So there DOES NOT exist any PC that is certified being compatible with Windows 11. windows 11 is still a dream imagined by Microsoft, without any serious base (and without any serious documentation): Microsoft has then NO right to change its support plan early for existing supported versions of Windows: Windows 11 DOES NOT exist, it is still something that may be abandoned or postponed for another year. Microsoft should have not modified at all ALL its documentation for ALL existing versions of Windows. And the documetntion bout Windows 11 contains serious contradictions. Even the Windows 11 eligibility program has been removed from their site, shoing that it also does not work, and no one is able to know what they will need to change (or not!). Windows 11 is just a "buzz", fake news made by Microsoft for a prematured OS that should stil lremain with its internal project code rather than a new product.
Windows 11 will NOT be ready at fall (and certainy aly not under the forged conditions announced on June 24). And Microsoft must not change its support plans for Windows 10, as it currently has NO replacement and NO clear plan of when it will be available and supported.