Build makes firmware I don't need

I build trunk for the Lantiq XRX200 soc (BTHH5a) on a Ubuntu 20.10 intel laptop using the openwrt build system.

During make I see this:

make[3] -C package/firmware/b43legacy-firmware compile


make[3] -C package/firmware/prism54-firmware compile

Neither firmware is selected in .config and both menuconfig and kernel_menuconfig show them as not selected, yet they get built anyway.

I wonder why?