Landscape material doesn't show correctly on ES3.1 if Landscape layer blend was implemented by using in Material function

Open the project attached to see the issue

• Create a landscape and landscape material, assign the material to the landscape
• Create a Material function, blend two colors(red and blue for example) by using Landscape layer blend node
• Feed this material function into the landscape material and plugin it to basecolor
• Paint the Landscape layer mask in viewport, make sure both layers has some portion visible
• Switch the Preview Render Level to High end mobile
• See the landscape's material shows black

Expectation: Landscape blend layers should work properly if using Material function to implement it