As a now former Auto electrician, I had an email from Stellantis to say that they no longer have to support vehicles over 10 years old unless it's for recalls. So Fiat, Citroƫn, Peugeot, jeep etc
At the time, I had a 2014 campervan in because it's module had forgotten how to switch on the dipped headlights or wind the windows back up after allowing them to be wound down
A replacement module from the manufacturer was no longer available. Second hand had already dried up. One dead retirement present.
Many GM era vauxhall models will be off the road as there are no more seatbelt pretensioners available.
Nissan don't supply many clock springs for some fairly recent models. This buggers the airbag system, instant mot failure
Mercedes need a different lights witch for the HID bulb headlight as it needs a headlamp washer for the mot. Now made of unobtanium
Renault had many parts on back order which means they no longer supply them - lots of fairly recent models rapidly disappearing
Unrepairable VAG vehicles due to immobilisers failing. They can be repaired via a donor car but the cost is immense - you need the abs module as well as ecu, clocks etc
Ā£250 flap motors - heating not clearing windscreens, add labour and it's absurd.
Having to remove dashboards or steering mechanisms to change heater blower motors, sometimes 10 hours labour (sounds familiar to headset bearing mechanics!)
I could go on, but I work with HGV now. Much easier