[SLO Bound] Portal-only customers receive error when accessing public Confluence spaces

Issue Summary

When customers from a Jira service management portal try to access a public Confluence space, they'll receive the following errors:

Page tree failed to load

Something went wrong

Refresh the page and try again. If this keeps happening, contact your space administrator.

Steps to Reproduce

1. Create a JSM project and add a customer
2. Make the related Confluence space to be publicly accessible
3. Also allow Anonymous access for the entire instance
4. Have the customer user access one of the space's pages, while authenticated into the portal

Expected Results

The user should be able to access the pages without problems, since they're public

Actual Results

• The page's contents may or may not load
• The following errors are shown:
  
• Errors in the browser's console:

  tti-polyfill.js:4 POST https://INSTANCE.atlassian.net/cgraphql?q=ExternalShareMetadataQuery net::ERR_ABORTED 401
  (anonymous) @ tti-polyfill.js:4
  fetch @ tti-polyfill.js:4
  d @ cfetch.ts:46
  (anonymous) @ createClient.ts:90
  run @ SSRMeasures.ts:23
  q @ createClient.ts:87
  (anonymous) @ bundle.esm.js:67
  e @ Observable.js:197
  value @ Observable.js:279
  e.consumeQueue @ bundle.esm.js:73
  (anonymous) @ bundle.esm.js:106
  setTimeout (async)
  e.scheduleQueueConsumption @ bundle.esm.js:103
  (anonymous) @ bundle.esm.js:37
  e @ Observable.js:197
  value @ Observable.js:279
  e.try @ bundle.esm.js:122
  e.start @ bundle.esm.js:110
  t.request @ bundle.esm.js:153
  (anonymous) @ bundle.esm.js:161
  e.try @ bundle.esm.js:122
  e.start @ bundle.esm.js:110
  t.request @ bundle.esm.js:153
  (anonymous) @ bundle.esm.js:161
  (anonymous) @ NetworkStatusLink.ts:66
  e @ Observable.js:197
  value @ Observable.js:279
  (anonymous) @ PreloadedQueryLink.ts:21
  Promise.then (async)
  (anonymous) @ PreloadedQueryLink.ts:30
  e @ Observable.js:197
  value @ Observable.js:279
  (anonymous) @ bundle.esm.js:11
  e @ Observable.js:197
  value @ Observable.js:279
  (anonymous) @ bundle.esm.js:864
  e @ Observable.js:197
  value @ Observable.js:279
  e.getObservableFromLink @ bundle.esm.js:1595
  (anonymous) @ bundle.esm.js:1630
  e.fetchRequest @ bundle.esm.js:1629
  (anonymous) @ bundle.esm.js:1146
  (anonymous) @ tslib.es6.js:100
  (anonymous) @ tslib.es6.js:81
  (anonymous) @ tslib.es6.js:74
  l @ tslib.es6.js:70
  e.fetchQuery @ bundle.esm.js:1092
  e.observeQuery @ bundle.esm.js:1460
  t.setUpQuery @ bundle.esm.js:388
  t.onSubscribe @ bundle.esm.js:366
  (anonymous) @ bundle.esm.js:96
  e @ Observable.js:197
  value @ Observable.js:279
  t.startQuerySubscription @ react-hooks.esm.js:222
  i.getExecuteResult @ react-hooks.esm.js:74
  t.execute @ react-hooks.esm.js:106
  v @ react-hooks.esm.js:380
  f @ react-hooks.esm.js:354
  p @ react-hooks.esm.js:397
  d @ useExternalSharePageQuery.tsx:51
  l @ useExternalSharePageDataProvider.tsx:84
  S @ PageShownPublicLinksEvent.tsx:27
  Xi @ react-dom.production.min.js:153
  xs @ react-dom.production.min.js:261
  mu @ react-dom.production.min.js:246
  vu @ react-dom.production.min.js:246
  su @ react-dom.production.min.js:239
  (anonymous) @ react-dom.production.min.js:123
  t.unstable_runWithPriority @ scheduler.production.min.js:19
  $o @ react-dom.production.min.js:122
  Ko @ react-dom.production.min.js:123
  Zo @ react-dom.production.min.js:122
  ru @ react-dom.production.min.js:230
  ga @ react-dom.production.min.js:163
  (anonymous) @ Loadable.tsx:184
  Promise.then (async)
  (anonymous) @ Loadable.tsx:183
  us @ react-dom.production.min.js:211
  cs @ react-dom.production.min.js:212
  wu @ react-dom.production.min.js:255
  t.unstable_runWithPriority @ scheduler.production.min.js:19
  $o @ react-dom.production.min.js:122
  _u @ react-dom.production.min.js:248
  su @ react-dom.production.min.js:239
  ru @ react-dom.production.min.js:230
  Vu @ react-dom.production.min.js:281
  (anonymous) @ react-dom.production.min.js:284
  cu @ react-dom.production.min.js:240
  Zu @ react-dom.production.min.js:284
  t.render @ react-dom.production.min.js:290
  (anonymous) @ index.js:125
  Promise.then (async)
  (anonymous) @ index.js:103
  59302 @ index.js:33
  d @ bootstrap:19
  (anonymous) @ app.Tx4tnYVoG7.js:13
  d.O @ chunk loaded:23
  (anonymous) @ app.Tx4tnYVoG7.js:13
  t @ jsonp chunk loading:98
  (anonymous) @ app.Tx4tnYVoG7.js:1
  Show 43 more frames
  

  react-dom.production.min.js:209 Error: Network error: Received status 401
      at new t (bundle.esm.js:63)
      at t.getCurrentResult (bundle.esm.js:159)
      at t.getQueryResult (react-hooks.esm.js:265)
      at t.i.getExecuteResult (react-hooks.esm.js:73)
      at t.execute (react-hooks.esm.js:106)
      at v (react-hooks.esm.js:380)
      at f (react-hooks.esm.js:354)
      at p (react-hooks.esm.js:397)
      at d (useExternalSharePageQuery.tsx:51)

Here's a video showing the problem happening:
jsm_customer_confluence_error.mp4

Workaround

If the page's contents don't load, reloading the page might work, but the page tree won't load.

Opening the page in a browser's incognito window, without logging-in to the customer portal will work.