How to work on a new git branch while previous branch waits for merge

Question

First, I am sorry to ask such question because I am sure it is a straightforward issue, still I found no solution an no way to understand what I am doing wrong. Some people asked almost exactly the same question (except the squash part) and the answer was obvious (rebase) but does not work for me.

I create a branch A, multiple commits, then I submit a merge request A->develop, with commit squash on.

While I wait for the MR to be accepted, I want to work on a new issue, from the branch A. So I create a branch B from branch A.

At some point branch A got merged into develop, and all the commit from A squashed into a single commit in develop.

Once my work on B is finished, I create a new MR B -> develop. But I can't because develop has been updated with changes from A. As I already have these changes in my branch B, because I created B from A, it should not be an issue. But it is.

No matter what I do from B:

git merge develop

or:

git rebase develop

I get an endless list of fake conflicts.

I suspect the issue is that the commit logs on my branch B includes all old commits of the branch A, whereas develop includes only one single squashed commit of the branch A. So they are not seen as the same commits and I get conflicts even though there are no actual conflicts. But I have no solution.

Any help would be appreciated. Thanks.