Kernel 5.4.0-40 killed my ethernet port

Hi all,
I just found that kernel 5.4.0-42 stopped my ethernet port on a lenovo x240 with an Intel port
description: Ethernet interface
product: Ethernet Connection I218-LM
on 20.04 LTS

I rolled back to 5.4.0-40 and it started working again.
Hoe do i report an issue ?

I am not experienced with bug reporting eater, yet. But here is some info about that: