Sometimes going up ladders with the auto climber ladder climbing descending feature disabled will make it stutter.

Could you give me a copy of your quark config?

https://pastebin.com/p0DWQ7br

Could you try this with only Quark?

Can't reproduce.

It seems to be some kind of incompatibility with another mod but I can’t pinpoint what is causing it. But it definitely happens in my modpack “Dimension Zero” maybe you can reproduce it in this and figure out what causes it. All the things that can affect ladders in this mod pack are quarks ladder feature client tweaks ladder feature and improvable skills ladder feature but even when trying them out separately it still happens.

OK I found the bug it’s not quark its quark in combination with client tweaks and iguana tweaks reborn
Probably something related to iguana tweaks heaviness configs or so. Sorry to take your time XD I have a modpack with over 200 mods in it and making them all work together when I get multiple people report bugs is sometimes too much for my little brain XD