This is attempting to start 2 drivers and send a get title command; looks like the second time a delete is sent, there's a problem.

This failure:
Selenium::WebDriver::Driver behaves like driver that can be started concurrently starts multiple drivers sequentially
Failure/Error: raise ex, cause: cause

 Selenium::WebDriver::Error::UnknownError:
   Failed to decode response from marionette
 Shared Example Group: "driver that can be started concurrently" called from ./rb/spec/integration/selenium/webdriver/driver_spec.rb:25

This config:
browser: firefox
driver: firefox
version: 137.0
platform: linux
ci: github
rbe: true
ruby: jruby 9.4.12.0 (3.1.4) 2025-02-11 f4ab75096a OpenJDK 64-Bit Server VM 17.0.11+9-LTS on 17.0.11+9-LTS [x86_64-linux]

Full logs: https://gist.github.com/titusfortner/e99b6c5987d65db1d4869138c85e6c1d