use this command:
Set-MailboxServer <ServerName> -DatabaseCopyAutoActivationPolicy Blocked
Why? Because it does what you want. :)
https://learn.microsoft.com/en-us/powershell/module/exchange/set-mailboxserver?view=exchange-ps
this command stop replication to that database, so only use when performing maintenance on the server and you dont want any replication to occur to it.
So dont use this one:
Suspend-MailboxDatabaseCopy –Identity DB-name \ server-name -ActivationOnly
Only use this when you want to also move any active DBs on that server to another before blocking autoamtic activation
Set-MailboxServer <ServerName> -DatabaseCopyActivationDisabledAndMoveNow $ True