Currently, Bitbucket cloud doesn't support "rebase + merge --no-ff" option for pull requests. Lacking of this option leads to non-linear commit histories since, we have multiple pull requests from multiple developers to our repositories in a regular day.

Latest update from Atlassian 2024-09-30

We've added support for the following additional merge strategies:

• Rebase + fast forward (BCLOUD-16610)
• Rebase + merge (BCLOUD-17881, BCLOUD-19186)
• Squash, fast forward only (BCLOUD-16338)

It's also now possible to sync a feature branch via rebase (BCLOUD-6202).

https://bitbucket.org/blog/branch-sync-merge-rebase