[5.x]: Copied entries are pasted to all activated sites, if section propagation method "Let each entry choose which sites it should be saved to"

What happened?

Description

Initial situation:

• Multisite setup with 7 independent sites
• Some of the sites also have language variants
• Section with propagation method "Let each entry choose which sites it should be saved to"
• The content of entries in this section is mostly only translatable into other languages

I have an entry that is published/activated on Site A, Site B, and Site C.
When I copy this entry and paste it into Site D, it is not only pasted to Site D but also to Sites A, B, and C.
As a result, the entry now exists twice on Sites A, B, and C.

The entry should be copied because the content for Site D needs to be similar but not identical, and editors should be able to adjust the entry for Site D without affecting Sites A, B, and C.

I would expect the copied entry to be pasted only into the site where I click the "Paste entry" button. In general, it cannot be correct that the entry is also added to Sites A, B, and C.

Craft CMS version

5.8.15

PHP version

8.3

Operating system and version

No response

Database type and version

MySQL 8.4

Image driver and version

No response

Installed plugins and versions

Reproduce this in Craft CMS 5.8.15 with seven independent sites, language variants, and a section using “Let each entry choose which sites it should be saved to.” Copy an entry active on Sites A, B, and C, paste it into Site D, and verify that the fix limits the pasted copy to Site D without creating duplicates on the other sites.