[Closed] Different domain not working properly

Background of the issue:
I am trying to use different domains for different languages on my WordPress site. The issue can be seen on this page: hidden link.

Symptoms:
When I choose to use different domains for different languages, it only works on some of the content. Some buttons work, but others do not, showing the language as /en instead of the expected domain hidden link. I have tried turning off all plugins, clearing the cache, and indexing links, but the problem persists. Currently, the EN domain is redirected to /en.

Questions:
Why does the different domain setup only work on some content?
How can I ensure all content uses the correct domain for different languages?