Problems with MS Teams app for videocalls

Hello, everybody!

I am trying to build an app (webview) for MS Teams. It should show up on the right hand side of video calls.

I am basing on this repo: https://github.com/pnp/generator-teams/tree/main/packages/generator-teams

During development, I am using NGrok (which is the way that is documented), and uploading the ZIP file directly (via "Manage Apps" -> "Upload").

Everything was working great until March the 1st, where, in the version for Work or School, I started getting, when adding the app to the call (after uploading the ZIP file), the following error:

"Something went wrong when loading tab configuration dialog, please try again later" (screenshot attached).

A few considerations:
- I have checked my server logs, and there is no request made to the configuration tab URL
- If I open the configuration tab URL on my browser, it works
- I have tried disabling CORS, but nothing
- I have tried replacing the NGrok based URL with a "live" one. Also no luck

- It all stopped working suddenly for everybody in my team, without us having changed anything in the code base.

- I tried removing the "bots" and "staticTabs" sections in the manifest. No luck.

Could anybody help pointing me in the right direction? Thanks a lot in advance!

Here is the manifest.json file:

{
  "$schema": "https://developer.microsoft.com/en-us/json-schemas/teams/v1.13/MicrosoftTeams.schema.json",
  "manifestVersion": "1.13",
  "id": "<ID_OF_THE_APP>",
  "version": "0.0.1",
  "packageName": "teams-voice",
  "developer": {
    "name": "Test Dev",
    "websiteUrl": "https://teams-voice-app.ngrok.io",
    "privacyUrl": "https://teams-voice-app.ngrok.io/privacy.html",
    "termsOfUseUrl": "https://teams-voice-app.ngrok.io/tou.html"
  },
  "name": {
    "short": "teams-voice",
    "full": "teams-voice"
  },
  "description": {
    "short": "TODO: add short description here",
    "full": "TODO: add full description here"
  },
  "icons": {
    "outline": "icon-outline.png",
    "color": "icon-color.png"
  },
  "accentColor": "#D85028",
  "configurableTabs": [
    {
      "configurationUrl": "https://teams-voice-app.ngrok.io/voiceTab/config.html?name={loginHint}&tenant={tid}&group={groupId}&theme={theme}",
      "canUpdateConfiguration": true,
      "context": [
        "channelTab",
        "privateChatTab",
        "meetingChatTab",
        "meetingDetailsTab",
        "meetingSidePanel",
        "meetingStage"
      ],
      "scopes": ["team", "groupchat"]
    }
  ],
  "staticTabs": [
    {
      "entityId": "<ID_HERE>",
      "name": "test",
      "contentUrl": "https://teams-voice-app.ngrok.io/Bot/test.html",
      "scopes": ["personal", "team"]
    }
  ],
  "bots": [
    {
      "botId": "<ID_HERE>",
      "needsChannelSelector": true,
      "isNotificationOnly": false,
      "scopes": ["team", "personal", "groupchat"],
      "supportsCalling": true,
      "supportsVideo": true,
      "commandLists": [
        {
          "scopes": ["team", "personal"],
          "commands": [
            {
              "title": "Help",
              "description": "Shows help information"
            },
            {
              "title": "Who am I?",
              "description": "Shows information about your Teams user"
            },
            {
              "title": "Mention me",
              "description": "Let the bot @mention you"
            }
          ]
        }
      ]
    }
  ],
  "connectors": [],
  "composeExtensions": [],
  "permissions": ["identity", "messageTeamMembers"],
  "validDomains": ["teams-voice-app.ngrok.io"],
  "showLoadingIndicator": false,
  "isFullScreen": false
}