Garret Rumohr wrote:

Fedora 34 (released) and RHEL 9 (upcoming) have removed support for deprecated kernel boot parameters without 'inst.' prefix.
This causes a failure to reach Anaconda to proceed with install when using the default templates.

see rdsoreport.txt lines 984-988

suggested resolution, add check for Fedora version >= 34 & RHEL >=9 to PXE templates to render expected kernel install parameters.

relevant info:
announcement sourcing: https://fedoraproject.org/wiki/Changes/Ignore_Anaconda_kernel_boot_parameters_without_inst_prefix
foreman community discussion: https://community.theforeman.org/t/fedora-34-kickstart-fails-to-make-it-to-installer-semi-resolved/23381