I think the following OSOT optimization needs to be reset to "0"

<step name="Turn off Thumbnail Previews in File Explorer"

      description="Enable this policy, Disable Thumbnail Previews in File Explorer."

      useCaseCatagory="VisualEffect" useCaseLevel="0"

      category="recommended" defaultSelected="true" runOnOs="16">

  <action>

    <type>Registry</type>

    <command>ADD</command>

    <params>

      <keyName>HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer</keyName>

      <valueName>DisableThumbnails</valueName>

      <type>REG_DWORD</type>

      <data>1</data>

    </params>

  </action>

</step>

André