This works by changing the blast resistance and break time values for deepslate blocks using reflection. They are all changed to their closest stone counterpart block. On it's own, this mod will only work on singleplayer, but I have created a paper plugin that allows this to work on servers.
You can toggle the functionality through the forge modmenu, but it does not save.
This mod probably won't recieve any support, but it is so simple im sure anyone could figure out how to update it or add/remove blocks.
Thanks to this blog for explaining how to connect a gui to the forge modmenu.
You can find the fabric version of this mod here.