That's one of its traditional variants. As Chinese characters has been changing forms throughout thousands of years, there were always some variants.
Today, the variants are usually only used in calligraphy or art works. Here, you can see many variants of 直.
Many characters have different variants. Variants of the same character may have different encodings (e.g. 青 and 靑, 高 and 髙, they are different in Unicode), but they may also be encoded into the same place. For these two variants of 直 concerned here, which character is shown is up to the font that the software chooses.