To provide the ability to prevent developers from pull request creation to a particular branch

I have a project repository on a bitbucket server behind a proxy. I am the administrator for the repository in concern. The ask was to freeze a particular release branch (say, release/1.0) and create a new release branch (say, release/2.0) branching out of release/1.0.

Is there a way I can prevent the developers from creating a pull request for merging their feature changes to release/1.0? Instead, they should be creating pull requests to merge their changes only to release/2.0.

Like in the pull request creation page, the target branch dropdown should not show the value - release/1.0. But it should show release/2.0.