Who is the calligrapher who started to change the font from official script to regular script?

From the perspective of font structure, regular script is similar to official script, but it changes the writing method of official script strokes, from flat official script to basic square regular script, which is called "square character". Regular script is also called official script and original script, which shows that regular script is a regular script for people to learn and use. The earliest regular script writer was Zhong You in the late Eastern Han Dynasty. In his handed down works, the brushwork of official script is still reserved. Regular script experienced many changes in Wei, Jin, Southern and Northern Dynasties, and was basically finalized after Sui and Tang Dynasties. After the script is finalized, it is quite exquisite and rigorous in strokes and structure, such as the works of Ou Yangxun, a famous calligrapher in the Tang Dynasty.