Found this in tests (https://github.com/Telegram-Mini-Apps/telegram-apps/blob/d7014effa88abf07a0c4ba271a9e54682b3c09e3/packages/transformers/src/validation/isLaunchParamsQuery.test.ts#L7C31-L7C1496, https://github.com/Telegram-Mini-Apps/telegram-apps/blob/d7014effa88abf07a0c4ba271a9e54682b3c09e3/packages/transformers/src/validation/isLaunchParamsQuery.test.ts#L19). It is working perfect for me:

mockTelegramEnv({
  launchParams:
    "tgWebAppData=user%3D%257B%2522id%2522%253A279058397%252C%2522first_name%2522%253A%2522Vladislav%2522%252C%2522last_name%2522%253A%2522Kibenko%2522%252C%2522username%2522%253A%2522vdkfrost%2522%252C%2522language_code%2522%253A%2522ru%2522%252C%2522is_premium%2522%253Atrue%252C%2522allows_write_to_pm%2522%253Atrue%252C%2522photo_url%2522%253A%2522https%253A%255C%252F%255C%252Ft.me%255C%252Fi%255C%252Fuserpic%255C%252F320%255C%252F4FPEE4tmP3ATHa57u6MqTDih13LTOiMoKoLDRG4PnSA.svg%2522%257D%26chat_instance%3D-9019086117643313246%26chat_type%3Dsender%26auth_date%3D1736409902%26signature%3DFNWSy6kv5n4kkmYYmfTbrgRtswTvwXgHTRWBVjp-YOv2srtMFSYCWZ9nGr_PohWZeWcooFo_oQgsnTJge3JdBA%26hash%3D4c710b1d446dd4fd301c0efbf7c31627eca193a2e657754c9e0612cb1eb71d90&tgWebAppVersion=8.0&tgWebAppPlatform=tdesktop&tgWebAppThemeParams=%7B%22accent_text_color%22%3A%22%236ab3f2%22%2C%22bg_color%22%3A%22%2317212b%22%2C%22bottom_bar_bg_color%22%3A%22%2317212b%22%2C%22button_color%22%3A%22%235289c1%22%2C%22button_text_color%22%3A%22%23ffffff%22%2C%22destructive_text_color%22%3A%22%23ec3942%22%2C%22header_bg_color%22%3A%22%2317212b%22%2C%22hint_color%22%3A%22%23708599%22%2C%22link_color%22%3A%22%236ab3f3%22%2C%22secondary_bg_color%22%3A%22%23232e3c%22%2C%22section_bg_color%22%3A%22%2317212b%22%2C%22section_header_text_color%22%3A%22%236ab3f3%22%2C%22section_separator_color%22%3A%22%23111921%22%2C%22subtitle_text_color%22%3A%22%23708599%22%2C%22text_color%22%3A%22%23f5f5f5%22%7D",
});