To my eye it looks like someone trying to pull the glass out with there hands using there feet as a brace.Love this sort of thing everybody has got a different idea as to what it is .
Dave
Windows 10 Pro 64 bit
AORUS B550 Master Motherboard
GeForce RTX™ 2070 GAMING OC 8G
AMD Ryzen 9 5950X 16-Core Processor 3.40 GHz
128 GB DDR4 RAM
3840 x 2160 ,60 Hz