The thing with Tasha is that everything is completely optional. The additional spells for say the Sorcerer are optional spells for that class. The additional spells in Xanathar and other sources are additional spells they aren't spells which have suddenly been Wizard only spells which can now be used by a Sorcerer. So I thought there needed to be some way to distinguish that. I could probably remove the (New) from the new spells but I'd need to look at why I did that and what impact that has on the character wizard.