Squash merge commit not shown correctly in graph view

Summary

I'm running a self-hosted instance. I expect the repository graph view to indicate that the commits of the feature branch were merged into master by displaying an arrow pointing from feature to master.

Instead, I see no connection between feature and master in the graph view. However, there is no difference between feature branch and master using diff.

Steps to reproduce

Create a feature branch from master. Commit multiple changes to the feature branch Merge the feature branch into master using the "Squash" option with squash commit when merge request is accepted.

Example Project

From the figure below I would have expected and single arrow pointing to master from feature branch when pressing Merge from the merge request. The merge request was created as usual from the feature branch represented in magenta. However, as you can see from the graph view, the merge appears like an additional branch (green line) and the feature branch doesn't appear to be merged into master. Indeed, going into Branches the feature branch doesn't appear to be merged as it is supposed to be.

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Expand for output related to the GitLab application check

Checking GitLab subtasks ...

Checking GitLab Shell ...

GitLab Shell: ... GitLab Shell version >= 13.14.0 ? ... OK (13.14.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful

Checking GitLab Shell ... Finished

Checking Gitaly ...

Gitaly: ... default ... OK

Checking Gitaly ... Finished

Checking Sidekiq ...

Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1

Checking Sidekiq ... Finished

Checking Incoming Email ...

Incoming Email: ... Reply by email is disabled in config/gitlab.yml

Checking Incoming Email ... Finished

Checking LDAP ...

LDAP: ... LDAP is disabled in config/gitlab.yml

Checking LDAP ... Finished

Checking GitLab App ...

Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
8/7 ... yes
8/9 ... yes
16/10 ... yes
8/11 ... yes
23/12 ... yes
23/14 ... yes
24/16 ... yes
24/17 ... yes
28/21 ... yes
38/22 ... yes
19/23 ... yes
28/24 ... yes
30/25 ... yes
46/26 ... yes
38/27 ... yes
19/29 ... yes
47/30 ... yes
72/31 ... yes
19/33 ... yes
53/34 ... yes
30/35 ... yes
8/36 ... yes
57/37 ... yes
8/38 ... yes
59/39 ... yes
10/40 ... yes
61/41 ... yes
59/43 ... yes
59/44 ... yes
38/46 ... yes
2/47 ... yes
38/48 ... yes
8/49 ... yes
53/50 ... yes
46/51 ... yes
57/53 ... yes
71/54 ... yes
72/55 ... yes
50/56 ... yes
Redis version >= 4.0.0? ... yes
Ruby version >= 2.7.2 ? ... yes (2.7.2)
Git version >= 2.29.0 ? ... yes (2.29.0)
Git user has default SSH configuration? ... yes
Active users: ... 33
Is authorized keys file accessible? ... yes
GitLab configured to store new projects in hashed storage? ... yes
All projects are in hashed storage? ... yes
Elasticsearch version 7.x (6.4 - 6.x deprecated to be removed in 13.8)? ... skipped (elasticsearch is disabled)

Checking GitLab App ... Finished


Checking GitLab subtasks ... Finished