Hello, this is actually normal. It's also not specific to my kernels.
Here's an email thread from 2015 with someone from Parabola also seeing it:
https://lists.gnu.org/archive/html/libreboot/2015-11/msg00009.html
In the case of the other about i915 I expect that it's related to libreboot
not having the proprietary option ROM included and is a non-issue since the
Intel graphics can be used without it.
So it's all related to coreboot/libreboot, not the kernel, and the warnings
can be ignored because your computer will continue to operate normally
regardless.
