ScrollView doesn't scroll up on new line in TextInput

Start by running the mandatory reproducer with npm install and npm run ios, then trace the iOS Fabric TextInput and ScrollView behavior involved in the first newline. Done means an auto-growing multiline TextInput causes the surrounding ScrollView to scroll to the appropriate position immediately on the new line, without requiring another character or newline.

Description

When an auto-growing multiline TextInput inside a ScrollView gets a new line, the ScrollView is not scrolled up. Only after inserting another new line or a character the ScrollView scrolls to the appropriate position

Steps to reproduce

1. Install the repro with npm install
2. npm run ios
3. Start typing text with each character in the new line

(See video attached)

React Native Version

0.86.0

Affected Platforms

Runtime - iOS

Areas

Fabric - The New Renderer

Output of npx @react-native-community/cli info

System:
  OS: macOS 26.6.2
  CPU: (11) arm64 Apple M3 Pro
  Memory: 153.44 MB / 18.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 24.18.0
    path: /Users/oleksiibulenok/.nvm/versions/node/v24.18.0/bin/node
  Yarn:
    version: 1.22.22
    path: /Users/oleksiibulenok/.nvm/versions/node/v24.18.0/bin/yarn
  npm:
    version: 11.16.0
    path: /Users/oleksiibulenok/.nvm/versions/node/v24.18.0/bin/npm
  Watchman: Not Found
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.5
      - iOS 26.5
      - macOS 26.5
      - tvOS 26.5
      - visionOS 26.5
      - watchOS 26.5
  Android SDK:
    API Levels:
      - "34"
      - "35"
      - "36"
    Build Tools:
      - 34.0.0
      - 35.0.0
      - 36.0.0
    System Images:
      - android-35 | Google Play ARM 64 v8a
      - android-36 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2025.1 AI-251.26094.121.2512.13991807
  Xcode:
    version: 26.6/17F113
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.14
    path: /Users/oleksiibulenok/Library/Java/JavaVirtualMachines/jbr-17.0.14/Contents/Home/bin/javac
  Ruby:
    version: 2.7.6
    path: /Users/oleksiibulenok/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.1.0
    wanted: 20.1.0
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.86.0
    wanted: 0.86.0
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

N/A

MANDATORY Reproducer

https://github.com/abulenok/MultilineGrowRepro

Screenshots and Videos

https://github.com/user-attachments/assets/23aacdd2-168d-495e-9e55-f99dc00c2fdb