The so-called new one on the left might actually be a clamp from one of their other famesets, and not standard with LCR-018D.  LC might have just sent it to the OP to try and help fix his slippage issue.  Note that the clamp on the left is not the same size as the one on the right, OP how well does it mate with the LCR-018D frame as the silver faced clamp looks to be shorter?

I think it just appears to be different sized on the picture because the bolts were screwed in different amounts. Tomorrow I can measure. Nevertheless it fits perfectly. And I don’t think it’s only so-called new, because they told me that the engineers initially thought the seatpost itself were the problem (thus the new grippy version), but found out later that the clamp design is the main problem. The new surface looks milled and is really sharp.

I haven't heard about a new clamp - has this been confirmed?

Not sure how new it is, but the old one is black on the inside and the new one is blank metal (on the friction side) with sharper edges.
I asked them about the issue - still had slippage at 9,5 nm, upgraded seatpost (grippy texture) and carbon paste. So they asked me to make a video demonstrating the slippage and then did send it to me for free.

Do you have any tips?

Grind the contact area with a coarse grit. After I did this I had no more skidding.
Btw the same goes with the seatpost clamp. After I sand it down I had no slippage anymore, almost as good as the new designed clamp.

But how much should I cut under the top of the stem ? From what I’ve seen the top of the stem should be « above » where i will cut the fork

Rule of thumb: never cut below the upper handlebar screw. Above that, you are in principle free to choose.

[...]I’ve said this 20 times on this thread, using height and inside leg measurements to buy frames is absolutely ridiculous, but people keep posting these two measurements thinking it will ensure a good fit.

Not everybody has access to a bike fit, and even if: three bike fitter will tell you three different measurements. Probably even wildely apart from each other. One has to start somewhere to gather experience.

Nice finish! I also thought about choosing crystal for more than a second.
And I placed my order 4 days later, so the exiciement grows.
Nice name btw.

I placed the order on 28th January. Paid on 29th.
Wendy told me that I will receive about March 25th --April 10th.
On March 27, I was told that it would be shipped in mid-April.
Last week I got the photos und this week on monday Wendy send the trackingcode.

I assume you actively asked for the top tube mounting points, right?