My apologies for the confusion. I should have checked part numbers before posting the previous reply.
("Burnside Bridge") is a retimer and ensures signal integrity when traces get too long. It is not a controller, and is not responsible for the Thunderbolt signal to exist in the first place.
Intel's Thunderbolt 4 controllers ("Maple Ridge
") are JHL8340
. Apple's controller is not a discrete component, it is part of the M1/M2 SoC, and probably has no name or nomenclature on its own. Apple does not use and has never used Maple Ridge in any Mac, so there is no driver for Maple Ridge in any version of macOS—not even the AppleSilicon version which supports Thunderbolt 4.
So M1 Macs used a JHL8040R retimer with Apple's Thunderbolt 4 controller, but M2 Macs now use a U09PY3 retimer instead. Whatever the reason, we should probably not try to see too much into the replacement of a $2.90 part.
It could be part of grand strategic decision to cut all ties with Intel, or it could just be that the mysterious U09PY3 is a a cheaper $2.60 part and/or a more sober 0.65 W part (instead of 0.75 W) than Burnside Bridge (JHL8040R is not
Gigabyte CG-Maple Ridge
AsRock Thunderbolt 4 AIC
MSI Thunderbolt 4 8K
all using JHL8540, which macOS does NOT support.