Add all tags in vanilla block to modded block

I want to copy all the tags in a vanilla block (namely sand) to a modded block I added.

To get the sand block tags I'm using

Blocks.SAND.builtInRegistryHolder().tags()

and calling it in a BlockTagsProvider class which was added to the DataGenerator in the GatherDataEvent.

The problem is that that line of code returns an empty stream. Anyone knows how else can I get the tags of a block, or any other way to implement this?