when I first saw the picture of the coin, I thought that the indiction has been erased. Then I looked up the description of the auction house and found that this is exactly what they suggested (Indiktionsbuchstabe getilgt).
However the auction house suggests that the letter has been erased from the die, while I think that it has been erased from the coin itself.
The remnants of a capital
are still visible. The matter reminds me of a solidus of Phocas I have posted in the fake section, which also has been reworked in an absolutely professional way to sell it as a rare thing.
I believe that the Heraclius solidus in question is a normal type of indictional year 10 which has been fraudulently altered in modern times and thus is destroyed in part.