Have noticed hundreds and hundreds of messages like this over the past two or three F35 kernel updates (via dnf):
hardlink: cannot link /usr/src/kernels/5.15.7-200.fc35.x86_64+debug/./net/mptcp/Kconfig to /usr/src/kernels/5.15.5-200.fc35.x86_64+debug/./net/mptcp/Kconfig.hardlink-temporary: File exists
hardlink: cannot link /usr/src/kernels/5.15.8-200.fc35.x86_64/./net/mptcp/Makefile to /usr/src/kernels/5.15.5-200.fc35.x86_64+debug/./net/mptcp/Makefile.hardlink-temporary: File exists
System boots from new kernels with no apparent issues.
Thanks.