GRub 2.06 and W10 bitlocker : seems to create unexpected new coexistance problem. Any advice?

[Eric Valette]

Hi,

I updated the debian bootloader part of a laptop with W10 and bitlocker 
enabled and debian bulleyes with the grub 2.06 version.

I did it the same way as I did with the first installation :
        1)  suspending bitlocker (not disabling as i would require
        disk decryption)   before the install,
        2) updating grub related pacakges only,
        3) and reenabling bitlocker after grub install.

This is typically what Windows10 itself does when updating some 
efi/bios/drivers components.

So far (before 2.06), it worked like a charm. I had put all related 
shim/grub package on hold just to control the upgrade, enabling me to 
perform bitlocker suspend before the upgrade, upgrade, put on debian 
package on hold again and renable bitlocker on Windows. Upgraded the 
kernel several time, changed module options and so on...

It did the same with 2.06, and I tough it worked or at least I had the 
impression it did. But today, without any other grub/efi/ related 
upgrade, Windows asks for the bitlocker key saying some 
software/hardware components changed.

I know company admin have ways to recover the keys so I do not worry to 
much about getting back access to W10 files again but I'm annoyed as I 
have no clue off what triggered bitlocker problem (I mean except the 
suspected upgrade to 2.06, but that I performed the same way I did 
during debian bulleyes initial install (2 bulleyes copies on two disk on 
the same PC) that worked flawlessly for 6 months or so.

I know grub 2.06 has TPM support and measured boot enhancement but do 
not understand how it can mess with bitlocker as long it is suspended 
during the operation. Of course if TPM itself is used and its content 
content is modified, and beitlocker notice it some problems may happen. 
I just hope the new grub does not touch efi config that windows may 
watch/inspect after upgrading the boot system itself otherwyse I will 
need to re-enter my key and annoys the W10 admin again and again.

Any clue feedback or advices?

Please CC me : I'm not subscribed

-- eric