Navigation: Space-between justification doesn't work

[jasmussen]

Description

Setting a navigation block to space-between does not have an effect:

It appears to be related to the width of one of the containers:

Step-by-step reproduction instructions

Insert a navigation block. Add 2 or 3 items. Set it to justified space-between, and note how it doesn't visually appear different from justified left.

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes