Figured it out.
First off: I'm an advanced user - i always run with UAC hard disabled, and many other non-safe bad security convience tweaks average users shouldn't do. But yea i'm a veteran in IT so enjoy breaking/fixing this stuff.
Anyways here's what's happening:
Win11 has a weird/bad new results when you disable UAC as you can no longer can't fully disable it (well hopefully we can, just not sure how yet). Instead with never notify on and enableLUA, on an user account with admin privileges.. Somethings just silently fail , others manager to elevate, others manage to elevate properly. The ones that fail i need to tick the advanced or compatibility option to always run at admin. Process hackek in particular here, as it can't kill a lot of stuff without it. In it's case - and regular task manager as its launched from it, it's actually running fully as if it's logged in as administrator, not just an elevated users.
What his means is, it's pulling all it's HKCU reg keys from that account, and startallback seems to just emulate this keys effects (without actually setting it):
HKEY_CURRENT_USER\Software\Classes\CLSID\{86ca1aa0-34aa-4e8b-a509-50c905bae2a2}\InprocServer32
But only for the current user, so when you launch certain apps which need to run as administrator (process hacker, void tools everything - without service mode, or even windows regular task manager if you need to kill some semi protecte process) - it will launch explorer as admin, and thus not have startallbacks registry hacks/settings. (The default shows the command bar, thus why it's showing, and why the new context menu is appearing)
So I un-disabled the administrator account, set up startallback same as I like on my regular account, and added said key, and then logged out and back to my account. And yep all working as expected now.
Hopefully there is some system wide way to hard disable that menu in a different way. Else i guess to fix this for the average used you'd have to have the installer hack the admins account HKCU reg hive to apply this tweak.