[data grid] Clicking a longText column's expand button triggers a form submission

[flvinny]

Steps to reproduce

Steps:

1. Open this link to live example: https://stackblitz.com/edit/5vsfaz2j?file=src%2FDemo.tsx
2. Expand any of the cells under the column called "bio"
   • A dialog should pop up, indicating that the form was submitted

Current behavior

The expand button on the longText column submits the parent form.

Expected behavior

The expand button should not affect any form encapsulating it.

Context

No response

Your environment

npx @mui/envinfo

    OS: Windows 11 10.0.26200
  Binaries:
    Node: 24.3.0 - C:\Users\DSI30\scoop\apps\nvm\current\nodejs\nodejs\node.EXE
    npm: 11.4.2 - C:\Users\DSI30\scoop\apps\nvm\current\nodejs\nodejs\npm.CMD
    pnpm: Not Found
  Browsers:
    Chrome: Not Found
    Edge: Chromium (140.0.3485.54)
  npmPackages:
    @base-ui/utils:  0.2.4 
    @emotion/react: 11.14.0 => 11.14.0 
    @emotion/styled: 11.14.0 => 11.14.0 
    @mui/core-downloads-tracker:  7.2.0 
    @mui/icons-material: 7.0.2 => 7.0.2 
    @mui/lab: ^7.0.0-beta.14 => 7.0.0-beta.14 
    @mui/material: ^7.2.0 => 7.2.0 
    @mui/private-theming:  7.2.0 
    @mui/styled-engine:  7.2.0 
    @mui/system:  7.2.0 
    @mui/types:  7.4.8 
    @mui/utils:  7.3.5 
    @mui/x-data-grid: ^8.9.1 => 8.28.5 
    @mui/x-data-grid-premium: ^8.27.0 => 8.28.5 
    @mui/x-data-grid-pro:  8.28.5 
    @mui/x-date-pickers: ^8.9.0 => 8.28.5 
    @mui/x-date-pickers-pro: ^8.27.0 => 8.28.5 
    @mui/x-internal-exceljs-fork:  4.4.3 
    @mui/x-internals:  8.26.0 
    @mui/x-license:  8.26.0 
    @mui/x-telemetry:  8.20.0 
    @mui/x-tree-view: ^8.27.0 => 8.28.5 
    @mui/x-virtualizer:  0.3.4 
    @types/react: 19.1.2 => 19.1.2 
    react: 19.1.0 => 19.1.0 
    react-dom: 19.1.0 => 19.1.0 
    typescript: 5.8.3 => 5.8.3 

Search keywords: longText form submit onSubmit

Order ID: 125366

[siriwatknp]

Thanks for the report — fix up in #22450.

[github-actions]

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@flvinny Thanks again for creating this issue! If you have a moment, we would love to hear your thoughts on how we handled it with this short feedback form.