Problem of parser when analyzing data from an external API

When requesting a server action directly, everything works fine and there are no problems:

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If I access the same server action from another application using an API action:

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I will get the data correctly:

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However, on the frontend there are problems with the analysis of expressions used in the repeat:

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Repeat is displayed correctly, but the expressions inside it do not work. However, the application where the data comes from uses the same frontend, and no problems arise. Only if the frontend is used in a third-party application and the data comes through the API, there is a problem with parsing.

Why does such a problem arise and how can it be solved? I would be grateful for any idea.