Looks like a layer of skin was taken off.
A few of my cats over the years have had similar where it weeps constantly as the trapped fur pulls the scab open over and over as they move around and groom themselves until the underlying wound heals and the sticky, gooey mess of fur and scab come off.
GL.iNet travel routers would like to have a word with you.
They have multiple versions available.
https://youtu.be/7_vk6cpPtxA
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