Hello,
Since I didn't really found a good place to report this, here we are.
In the documentation about creating a block (https://mcforge.readthedocs.io/en/1.16.x/blocks/blocks/#basic-blocks), it specify to use the AbstractBlock.Properties#create method to get the object. But it is now the method AbstractBlock.Properties#of that must be used.
It got me a little confused so I supposed it should be fixed.