Further reading and that it is worth noting this is an old talk (2018) about an even older processor (~2001). This is still a worry but to my understanding is that nothing newer/modern has shaken out since and hackers/researchers have been looking still. The largest area of worry is more in the embedded/SoC world where it isn't a "big trusted (domestic) vendor" making your chips but someone new/less experienced/etc trying to make your cheap $0.03 IoT MCU "The S in IoT stands for Security" chips.