When you get an automatic feature or even only cumulative Windows 10 update with an activated BitLocker (password protected) system partition BitLocker will prompt you afterwards from the system tray that it is suspended. From here you can / have to manually enable it again.
This leads to the conclusion that it got automatically disabled during the update. Articles like this one implicitly confirm this and suggest that there are newer switches which aren't enabled by default and would only work in and TPM secure boot environment with which you can try to keep BitLocker active during updates. However, for a password protected BitLocker system partition they wouldn't work anyways.
I personally also remember updates where I wasn't even prompted once for the BitLocker password during an update restart so that I could effectively access windows (with an now suspended BitLocker encryption) without even typing in the BitLocker password. However this hasn't happened recently. For the last updates which suspended BitLocker you at least had to type in the password at the usual place right after reboot.
But would it be possible to bypass BitLocker in any way for someone who steals my notebook while powered on but locked when he just keeps it powered on for a couple of weeks/months until a restart will almost certainly come with a bigger update and now he simply could issue a reboot from the lock screen?
As soon as the decryption key would get written to the hard disk at any point in time automatically this would be fairly easy. The question is, is that the case?