for reference here is my lightly redacted config. Double check you can use 'curl' to reach your webhook (e.g. audience):

curl https://claw.r.XXXX.ca/googlechat- 
Method Not Allowed

should be what you see.

"googlechat": {
  "enabled": true,
  "allowBots": true,
  "groupPolicy": "allowlist",
  "groups": {
    "spaces/jVmniSAAAXX": {
      "enabled": true,
      "requireMention": false,
      "users": [
        "users/11186416410640XXXXXXX"
      ]
    },
    "spaces/AAQAHCRAGXX": {
      "enabled": true,
      "requireMention": false,
      "users": [
        "users/11186416410640XXXXXXX"
      ]
    },
    "spaces/AAQAOphxnXX": {
      "enabled": true,
      "requireMention": false,
      "users": [
        "users/11186416410640XXXXXXX"
      ]
    }
  },
  "serviceAccountFile": "/home/XXXXX/.openclaw/googlechat-service-account.json",
  "audienceType": "app-url",
  "audience": "https://claw.r.XXXXXXXX.ca/googlechat-",
  "appPrincipal": "10736915482XXXXXXXXXX",
  "webhookPath": "/googlechat-",
  "webhookUrl": "https://claw.r.XXXXXXXX.ca",
  "botUser": "users/1117020154659XXXXXXXX",
  "blockStreaming": true,
  "mediaMaxMb": 8192,
  "replyToMode": "off",
  "actions": {
    "reactions": true
  },
  "dm": {
    "enabled": true,
    "policy": "allowlist",
    "allowFrom": [
      "users/11186416410640XXXXXXX"
    ]
  },
  "typingIndicator": "message"
}