Gcloud returns question marks instead of other languages’ symbols

I’m sending requests to google STT via gcloud (gcloud ml speech recognize-long-running) and when I do it on my windows computer everything is fine. However when I run it in a container (debian 10), response has question marks instead of russian symbols.
The beginning of response:

{  "@type": "type.googleapis.com/google.cloud.speech.v1.LongRunningRecognizeResponse",  "results": [    {      "alternatives": [        {          "confidence": 0.88946664,          "transcript": "???????...

I use Debian 10 (FROM mcr.microsoft.com/dotnet/core/aspnet:3.0) and use those commands to install gcloud:

RUN echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] https://packages.cloud.google.com/apt cloud-sdk main" | tee -a /etc/apt/sources.list.d/google-cloud-sdk.list
RUN curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key --keyring /usr/share/keyrings/cloud.google.gpg add -
RUN apt-get update && apt-get --yes install google-cloud-sdk

And I use those commands to set locale:

RUN apt-get update && apt-get install -y locales
RUN sed -i -e 
  's/# ru_RU.UTF-8 UTF-8/ru_RU.UTF-8 UTF-8/' /etc/locale.gen 
   && locale-gen
ENV LANG ru_RU.UTF-8
ENV LANGUAGE ru_RU:ru
ENV LC_LANG ru_RU.UTF-8
ENV LC_ALL ru_RU.UTF-8

Though I doubt it’s the problem with locale because I don’t see text with broken encoding, but text with question marks (symbol code 63).

Source: StackOverflow