Hide bookings calendars from GAL

Thanks, KirkLashbrook, in particular (and __Pavlo__ although yours is more effort)! 
The powershell command worked for me.

I don't understand how the Bookings thing works behind the scenes, but I had hoped to see them listed in Exchange Admin Center so that I could choose each and do a "hide from Exchange/GAL" - but that was not the case.
I was only able to see these Bookings accounts within Entra (Azure), which has no "hide from Global address list/exchange" option.  I wish Entra had the "Attributes" tab like AD on-premises has, which would allow us to set the "msExchHideFromAddressLists" that is there, like we old timers are used to doing.. 
It seems Microsoft tries to dumb down consoles to be "easy" (presumably for entry level admins), but they must keep expanding functionality from whiners like all of us here, and the consoles become cluttered with menus' deep options, no longer simple, LOL 🙂  Particularly no longer simple when it seems we so often are resorting to Powershell .   Am I the only person out there who often needs guidance to find the proper PS commands to get deep functionality accomplished?!

This worked for me:

Get-Mailbox -RecipientTypeDetails SchedulingMailbox -ResultSize:Unlimited | Set-Mailbox -HiddenFromAddressListsEnabled:$TRUE

You can hide automatically by changing the GAL filter : 

https://learn.microsoft.com/en-us/exchange/address-books/address-lists/configure-global-address-list-properties

And exclude mailbox with RecipientTypeDetails = SchedulingMailBox

You can also make a script that hide them.

You can hide calendars from GAL by Powershell 7 commands: 

1. Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
2. Install-Module -Name Az -Scope CurrentUser -Repository PSGallery -Force
3. Connect-AzAccount
   
4. Connect-ExchangeOnline -UserPrincipalName email address removed for privacy reasons
5. Set-Mailbox -Identity email address removed for privacy reasons -HiddenFromAddressListsEnabled $true
6. Disconnect-ExchangeOnline

This deserves way more votes.