When placing a sign on a replaceable block, such as snow, tallgrass, etc.

The sign sometimes automatically attaches to the blocks surrounding it if looking at the replaceable block at a rather horizontal angle.

When placing looking more vertically down, the sign places as normally.

See attached Video for steps to reproduce.

Expected behavior.

When placing a sign on a replaceable block (cursor intersects with hitbox) the sign always becomes a standing sign.

When placing a sign against another block, not intersecting the cursor with the hitbox of the replaceable, but instead the other block. Then it can turn into a wall sign.

So depending on the aim location of the cursor, if it clearly selects the replaceable block, it becomes a standing sign. Only if the actual 'block' selected is also the block the sign will be attached to as wall sign, should it do so.