Can we remove firebase tag on thunkable cross platform?

You are right, Thunkable X does not have the same functionality as Classic, but it also has advantages.

Yes, for working with Firebase Thunkable X does not have the same number of blocks, but this does not mean that using it is impossible to work with Tag. It just does it in a different way - by rewriting the nodes. You cannot delete a node, but you can change the parent node so that it does not have this child node.