Why does 'fresh start' still install bloatware from OEM?

I thought it would come clean with standard Windows 10 installation? In my case, the OEM is HP and the Windows is SL x64.

I was using Get Started from Windows Defender Security Center app.

OEMs often include a custom configuration so that doing a reset will include their software and, more importantly, their device-specific drivers. This means that resetting the PC is their 'Factory reset' option without the need for a separate recovery partition. That could use up 10-15GB of your hard drive , as was the case for previous versions of Windows.

If you make a Recovery Drive to a USB with the 'include system files' box ticked this will include these OEM customisations. This is the Windows 10 equivalent of making the OEM factory restore media.

If you want a plain-vanilla Windows 10 without anything from the OEM you'll need to do a clean install using media downloaded from Microsoft.

I have no direct experience with this, but it appears this post may be relevant if your PC has UEFI firmware and if HP has embedded an OEM executable in the “Windows Platform Binary Table” (WPBT) section of the PC’s UEFI firmware to install HP's drivers and bloatware. The post describes how to verify whether your system is set up this way by checking for a file named wpbbin.exe in the C:\Windows\system32 directory.

(The post also links to a How-to-Geek article with more detailed information.)

Click on Get Started again and read the blue box that pops up. It states in the blue box: "Any store apps installed by your manufacturer will also be kept". It did exactly what it stated it was going to do.