Mobs can spawn on oxidized or waxed copper grates

The bug

The 23w43a changelogs say "Hostile mobs cannot naturally spawn" on copper grates. However, they spawn on oxidized and/or waxed copper grates.

Steps to reproduce

1. Set time to night.
2. /fill ~-20 ~ ~-20 ~ ~ ~ minecraft:weathered_copper_grate
3. Go up a few dozen blocks.
4. Wait.

Expected result

Mobs wouldn't spawn.

Observed result

Mobs do spawn.