Hello @Filip Noga
Based on the information you provided, it seems like the issue might be related to the fact that you're making changes to your function code directly in the Azure portal editor.
Sometimes, the portal editor can cache the old version of your code, which can cause issues like the one you're experiencing.
To resolve this issue, I recommend that you try publishing your updated code to your function app using a deployment platform like Visual Studio Code or Azure DevOps.
This will ensure that the latest version of your code is deployed to your function app and that the old version is not cached.
If you prefer to continue using the Azure portal editor, you can try clearing your browser cache and cookies, or using a different browser to access the portal.
This can sometimes help to clear any cached data that might be causing the issue.
I hope this helps