I drove the car from the NYC area to Burlington, VT this weekend with 2.8.9. I can confirm that it does indeed slow down on straights when near highway exits saying it is slowing down for the curve. It doesn't do it every time but it seems to struggle with low light, rain and/or faded lane lines on the pavement. It also went for a number of stretches with DD pro only working in the left lanes and not the right lanes. It was raining or damp for the drive so maybe it was sensors (although I wasn't getting any sensor notifications). It also used 300 miles of stated range for a 209 mile trip in mid-40 degree weather at ~70 mph.
It also doesn't like traffic ahead of it in a different lane drifting toward the Lucid's lane. Rather than drift a bit itself, it slows down a lot which comes as a surprise to the driver of the Lucid and other human drivers nearby (and probably FSD Teslas).
I'm being patient with Lucid on the FSD software. I want them to get Gravity and the mid-sized launched successfully and achieve economic viability as their first goal. Then they can run hard at refining the software. They have the best cars - EV or otherwise. They succeeded in that far beyond anyone else. The software will follow. And FWIW, I don't think anyone will catch up to Tesla or GM FSD systems for a quite a while. They will eventually as ICE cars will be collecting all the driving data too (if they aren't already). Lucid may have to partner with someone if they want to make a big leap in FSD.