Inconsistent comment toggle in in `.ini` / `.properties` depending on which file is opened first

[alexchexes]

Does this issue occur when all extensions are disabled?: Yes

Version: 1.108.2 (user setup)
Commit: c9d7799
Date: 2026-01-21T13:52:09.270Z
Electron: 39.2.7
ElectronBuildId: 12953945
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Windows_NT x64 10.0.26100

Please reopen #116729 and/or #151655. The issue is real and reproducible. Below are a screencast and exact steps.

To Reproduce

Create two files in the same workspace: one .ini and one .properties. The contents can be anything, for example:

foo
bar

Part 1

1. Close all files and restart VS Code.
2. Open the .properties file first.
3. Toggle line comment. See that VS Code uses # in the .properties file.
4. Open the .ini file.
5. Toggle line comment. See that VS Code also uses # in the .ini file.

Part 2

1. Close all files and restart VS Code.
2. Open the .ini file first.
3. Toggle line comment. See that VS Code uses ; in the .ini file.
4. Open the .properties file.
5. Toggle line comment. See that VS Code also uses ; in the .properties file.

For the same two files, the comment character used by Toggle Line Comment depends on which file type was opened first.

Screencast

explorer_2026-03-02--15-41-48--715.mp4

[RedCMD]

can confirm

also notice ctrl+/ line commenting does not work in .ini on a blank line
EDIT: caused by editor.experimental.preferTreeSitter.ini
cc @alexr00

try disabling experimental.asyncTokenization

• Turns off asyncTokenization by default. Fixes #235344. Fixes #202938 #244217

[RedCMD]

the built-in npm extension also defines the language properties
but removing it doesn't seem to fix it

vscode/extensions/npm/package.json

Line 70 in d1c2013

"id": "properties",

enabling experimental.asyncTokenization actually fixes this issue

make sure to close all instances of VSCode
disable experimental.asyncTokenization