薯 is a Chinese character that appeared some time around the 6th century CE. By that time, the Roman emperor Theodosius I had closed all non-Christian temples, so the last known Egyptian hieroglyphs were written some time around 400 ce. There is almost no overlap.
In Chinese, 薯 was originally written 藷；薯 is a corrupt form that eventually supplanted the original word, probably some time around the 6th or 7th century CE. 藷（薯）originally meant sugar cane. Sugar cane originated in what is today New Guinea, and spread to China some time in the first millennium BCE, probably around the 4th century BCE.
According to what I have found online, Arabs introduced sugar cane to Egypt in 641 CE, or about one thousand years after it was first cultivated in China, over two hundred years after the last hieroglyphs were written, and roughly the time 藷 was corrupted into 薯.
I see no connection whatsoever between this character and Egyptian hieroglyphs.