Describe the bug

A layout shift occurs on the <DropdownMenu.SubContent> component during onmouseleave events. When the cursor leaves the SubTrigger or the SubContent area, the submenu container momentarily jumps or recalculates its position coordinates for a brief flicker before the exit transition completes or the component unmounts.

Although this behavior surfaced following the release of bits-ui@2.15.8, it appears to be specific to the shadcn-svelte implementation. While the issue is present in shadcn-svelte projects, it is not reproducible in a standard bits-ui reproduction StackBlitz template using the same version.

Reproduction

https://stackblitz.com/edit/github-5bwd9wq1?file=src%2Froutes%2F%2Bpage.svelte

Logs

System Info

System:
    OS: Linux 6.6 Ubuntu 24.04.4 LTS 24.04.4 LTS (Noble Numbat)
    CPU: (16) x64 AMD Ryzen 7 7800X3D 8-Core Processor
    Memory: 14.51 GB / 15.18 GB
    Container: Yes
    Shell: 5.9 - /usr/bin/zsh
  Binaries:
    Node: 24.13.1 - /home/user/.local/share/pnpm/node
    npm: 11.8.0 - /home/user/.local/share/pnpm/npm
    pnpm: 10.30.0 - /home/user/.local/share/pnpm/pnpm

Severity

blocking an upgrade