Hi @Mehmet KONUK ,
Welcome to Microsoft Q&A!
I created a ASP.NET Core Web App and could reproduce your issue.
Based on my testing, I found it is related to the setting: Tools > Options > Text Editor > Razor (ASP.NET Core) > General > Auto list members. But the setting is shown as grayed out.
So, I suppose it is designed like this in .cshtml file.
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