Creating a static web app for React app raises "Host key verification failed." error

**Describe the bug**

I have created a static web app. Chose there /src and build for react. Then I changed script to / and build. This is the YML file:
https://github.com/RedDuck-Software/Undas.Frontend/blob/main/.github/workflows/azure-static-web-apps-mango-pebble-0fb617803.yml

The pipeline never succeeds. One example is:
https://github.com/RedDuck-Software/Undas.Frontend/runs/7446967548?check_suite_focus=true

It also happens with other react repositories that I'm trying to make work.

The error that it gives is:
yarn install v1.22.15
[1/4] Resolving packages...
[2/4] Fetching packages...
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.
error Command failed.
Exit code: 128
Command: git
Arguments: ls-remote --tags --heads ssh://git@github.com/ethereumjs/ethereumjs-abi.git
Directory: /github/workspace
Output:
**Host key verification failed.
fatal: Could not read from remote repository.**
Please make sure you have the correct access rights
and the repository exists.

I have opened the link https://github.com/ethereumjs/ethereumjs-abi and the repository indeed exists and I can access it even if I don't have an account.

A clear and concise description of what the bug is.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'Azure Portal'
2. Click on 'Static Web Apps'
3. Create a Static Web App
4. Use "React" preset, SRC: "/", Build: "build"
5. Connect the following repository (or a clone of it): https://github.com/RedDuck-Software/Undas.Frontend/

**Expected behavior**
A normal repository would be deployed without a problem.

**Additional context**
The same way this project failed as well: https://github.com/RedDuck-Software/ProtagonistPad.Frontend
As you can see there, there is also SRC "/", Build: "build", preset React, and it's a normal React app.