Not sure if this is the correct process, but I submitted a bug report (request) to include the Realtek RTL8125 kernel module. I see this being a more requested enhancement for people using gigabit+ internet connections, which is becoming more common at least in the US with newer cable modems supporting 2.5 gbps network connections.
https://bugzilla.ipfire.org/show_bug.cgi?id=12559
I would be willing to try upgrading the linux kernel to kernel-5.9.9-ipfire-x86_64.tar.xz, but do not have the knowledge there to proceed.