Thank you all. You have all been a great help for what was a scary moment.
Everything should be genuine, chain and cassette are from authorised dealers and arrived in full packaging.
The Shimano rings will be going back on for now. I’m hoping Dura ace 12 speed chainrings will fit the Ultegra 12 speed crank so I can get the gearing needed for TTing and then just use an Ezdisc cover as mentioned above to hide the mismatch.
Otherwise I assume Rotor are a trusted brand that have been raced on?
I guess Alugear chainrings are fine when they are MTB sized and 1x. Their 2x big rings need a lot of work. They have emailed back saying they are reworking their chainrings to strengthen them and would like me to test those but I think I am just too scared to ever sprint on them again and I shouldn’t be afraid to ride my bike.