Symfony version(s) affected: 5.1.0

Description
Moving from sf 5.0 to 5.1 the LogoutHandlers become deprecated and you have to use listeners instead.

I have an issue with my session. I was writing something to my flashbag that later I was viewing this to the customers. Moving to a listener this does not seem to work.

How to reproduce
I have created a reproducer project here:

branch: master, version: v5.0

I have a handler that writes something to the flashbag that after the logout process it will be displayed to the user

I also have a test that validates this behavior.

branch: v5.1, version: v5.1

On the branch above I migrated the handler to a listener the test exists also on that branch but it fails.

concluding

Is this the expected behavior or os this a bug? If it is expected why is that?