Translate Web Pages does not collect any data.
The only communication is with Google (translate.google.com and translate.googleapis.com), Yandex (translate.yandex.net), Bing (bing.com) and DeepL (deepl.com) server.
These translation services (Google, Yandex, Bing and DeepL) can collect data to improve their services.
To translate, all content on the page is sent to Google, Yandex, Bind or DeepL servers.
For text to speech (tts) the text will be sent to Google.
The source code is available on Github.