Memory leak from changing mounted component's props

[teemingc]

Describe the bug

Changing the props of a mounted component following the guide at https://svelte.dev/docs/svelte/v5-migration-guide#Components-are-no-longer-classes seems to increase the memory usage without it ever being released. This affects SvelteKit navigation as we set new props on every navigation.

Reproduction

https://github.com/teemingc/svelte-memory-leak

Instructions are in the README.md

Memory leak still happens even when commenting out the <Counter> component

Logs

System Info

System:
    OS: macOS 26.3.1
    CPU: (8) arm64 Apple M1 Pro
    Memory: 124.92 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.22.0 - /Users/teeming/Library/pnpm/node
    Yarn: 3.2.3 - /Users/teeming/Library/pnpm/yarn
    npm: 10.9.4 - /Users/teeming/Library/pnpm/npm
    pnpm: 10.31.0 - /Users/teeming/Library/pnpm/pnpm
    bun: 1.3.9 - /opt/homebrew/bin/bun
  Browsers:
    Chrome: 145.0.7632.160
    Chrome Canary: 135.0.7048.0
    Firefox: 147.0.3
    Firefox Developer Edition: 130.0
    Safari: 26.3.1
    Safari Technology Preview: 26.0
  npmPackages:
    svelte: ^5.45.2 => 5.53.7

Severity

annoyance