Well Washington is balding on back of head, he's not on other quarters, and I don't think the letters under quarter are supposed to be there.
Your top pic is washed out but it appears it might be some die polishing going on that area. I cannot see the extra lettering you are talking about.
The bald spot, lol, is from the mint polishing the die. This is done on a regular basis in order to prolong the life of the die. This balding is nothing when compared to other coins. One of the most famous is the 1937-D Buffalo 3-leg nickel. The 4th leg was polished away. On more modern coins you will find a floating roof on the Lincoln Memorial as the roof supports have been polished away along with the designers initials. The cent is fairly common so inexpensive but the Buffalo will cost a minimum of $100 in a very worn condition. As for the letters under QUARTER, I’m not seeing them. Is that imagination of yours working overtime? Lol
I see what appears to be letters, very shallow under quarter. Clearer pic's would tell the story, good luck