I cannot for the life of me figure out what is the problem, but this corner often breaks my connected carts. It is a railline powered by powered rails, and it is a cart pulling a cart with chest. I've tried adjusting r=where the powered rails around there are in case it is because of going too fast or something, but it is still ongoing. This particular time that I finally decided it was worth an issue report, the cart derailed, and the cart with chest came backwards along the way it came, but, where the cart ended up is where they seem to typically end up. The line goes as if you are driving on the left side of the road, so, in the first picture, from the right side to the left side

It's most likely the sharp turn straight into a downward angle. There's some jank with slopes I still need to fix.

Hm... I tried making it less sharp by making it two blocks after going uphill rather than 1, but still have the issue.