Steps to reproduce:

1. Add the ger-DE language.
2. Create the following site access config:

           en:
               languages: [eng-GB]
               content:
                   tree_root:
                       location_id: 56
   
           de:
               languages: [ger-DE, eng-GB]
               content:
                   tree_root:
                       location_id: 57
   

           admin_group:
               languages: [eng-GB, ger-DE]
               page_builder:
                   siteaccess_list: [en, de]
   

   where location_id for each site access are folders under Home folder named respectively (both can be created in eng-GB language):
   Home
   ----en (location ID = 56)
   ----de (location ID = 57)

1. Create eng-GB Landing Page under the de folder.
2. Fill the form and click on Save draft.

Result:
v2.5
You will be matched with wrong site access, en site access is outside of de site's scope due to tree_root setting. You can observe it in the URL string at the top:

Editing:
http://localhost:8002/admin/content/preview/59/1/eng-GB/site_access/en?editorial_mode_bearer=

v3.3
Skip the 4th step. The landing Page draft will be automatically created in step 3. However, when hovering on the URL you will see that the tooltips show the wrong site access is matched (en).

Expected result:
You should be matched with de site access.