Pretty sure that’s a Gutenberg problem and not an ACF problem. The block editor wants to put EVERYTHING in that tiny sidebar on the right.
If you create an ACF block and assign the field group to the block, you will at least be able to fill out the fields within the block. If the fields are for a CPT, you can add that block to a block template for the CPT, so that it’s there automatically when you create a new CPT post.
There may be a way to force the field metaboxes to show up below the edit screen, but I’m not aware of it.
