What is the problem?

When deleting an associated talk page via the API (using the deletetalk parameter), the reason that is recorded for the talk page (in Special:Log, RecentChanges, etc.) is:

Deleted together with the associated page with reason: <reason>

This is not the same when undeleting, where Deleted together with the associated page with reason: is not included in the reason.

I guess they should be consistent.

Steps to reproduce problem

1. https://en.wikipedia.beta.wmflabs.org/wiki/Special:ApiSandbox#action=delete&format=json&title=Selenium_Echo_link_test_0.877682400562503&reason=This%20is%20the%20reason%20for%20the%20delete.&deletetalk=1
2. Submit
3. Look in https://en.wikipedia.beta.wmflabs.org/wiki/Special:Log (you will see something like below:)
   
4. https://en.wikipedia.beta.wmflabs.org/wiki/Special:ApiSandbox#action=undelete&format=json&title=Selenium_Echo_link_test_0.877682400562503&reason=This%20is%20the%20reason%20for%20the%20undelete.&undeletetalk=1
5. Submit
6. Look in https://en.wikipedia.beta.wmflabs.org/wiki/Special:Log (you will see something like below:)
   

Expected behavior: The undelete reason for the associated talk page is Undeleted/restored together with the associated page with reason: This is the reason for the undelete.
Observed behavior: The undelete reason for the associated talk page is This is the reason for the undelete. (exactly the same as the content page)

Environment

Wiki(s): https://en.wikipedia.beta.wmflabs.org MediaWiki 1.39.0-alpha (6876de7) 06:15, 6 April 2022.