How to pass a custom button in a drawer navigator, using the DrawerItemList in React Navigation v. 5?

For drawerLabel you have directly set an object which is wrong

  drawerLabel: (
    <BoldText style={NavigationStyles.arhiki}>Αρχική</BoldText>
  ),

This should be either a string or a function that returns a component, so you should change it like below

  drawerLabel: {()=>(
        <BoldText style={NavigationStyles.arhiki}>Αρχική</BoldText>
      )},

You can refer the docs https://reactnavigation.org/docs/drawer-navigator/#drawerlabel