But looking near the bottom of https://switchbrew.org/wiki/18.0.0 shows that another master key (master_key_11) has appeared, although it didn't increase the burnt fuse count, that which can make any new releases using this key may become...
For anybody who hasn't heard about the recent news, the sigpatches repo has been taken down due to a harsh DMCA claim by Nintendo. For now, if you're willing to mod your Switch on the latest firmware, do NOT update until new patches are created...