Can you post your about:support?

With this, Mozilla will have given more than 1.5 years of extra support compared to Chromium browsers. Supporting old operating systems has a development cost, and they put themselves at a disadvantage if they choose to support these old OSes for much longer.

People should really just update. Old, unsupported operating systems are unsafe to use.

My guess is a change in hardware.

Oh, does ESR not have mandatory extension signing? That is pretty interesting actually! I thought unbranded builds were the only way to go, but they lack automatic updates.