I had issues signing in to Firefox. I run No Script in my main browser and discovered bitwarden wanting to connect to hcaptcha.com but No Script extension blocks it by default. I had no issues signing into any other browser, since I do not have No Script installed on the others. I discovered this by visiting https://vault.bitwarden.com/ and saw the captcha script was blocked. I allowed it in No Script, then bitwarden browser extension would show the captcha.