Thanks, i also found this explanation.

• Anonymous trading may be important to large traders who don't want to provide clues to other traders that they are buying or selling.
• For instance, a large institutional buyer that's interested in acquiring millions of shares may not want to make their intentions known before they can complete the purchase. The risk is that smaller investors could bid up the price hoping to sell it to the institutional buyer for a quick arbitrage profit, or pennying could be used to unfairly gain execution priority.

https://www.investopedia.com/terms/a/anonymoustrading.asp