Words are clipped/broken/cut at the end of each line when opening a knowledge base article from the Service Desk portal

Issue description

Words are clipped/broken/cut at the end of each line when opening a knowledge base article from the Service Desk customer portal (word wrapping issue).

Steps to replicate

• Install Jira 8.13.0 with Service Desk 4.13.0
• Install Confluence 6.15.9
• Create an application link using Oauth 2.0 with impersonation between both applications
• Create a new space in Confluence, and create a page in this space containing a big paragraph
• Create a new Service Desk project in Jira
• Configure a knowledge bage in the project via the page Project Settings > Knowledge base, using the space created in Confluence
• Open the customer portal from the Service Desk project
• Search for any word that's included in the Confluence page
• Verify that the Confluence page is found, and that there is not "word wrapping" issue there:
  
• Now, click on the link to see the whole Confluence page

Expected results

The words should not be cut at the end of each line, like it's the case when integrating Jira with Confluence versions like

• 6.15.7
  
• 7.2.0
  

Actual results

The words are cut at the end of each line, and continue on the next line:

Notes

Issues was reproduced in 6.15.8, 6.15.9, but not in 6.15.7 nor 7.2.0 or any higher Confluence 7.x version.
So, it seems that:

• the bug was introduced in 6.15.8
• the bug somehow disappeared around 7.2.0, but it is not clear which exact version fixed this bug

Workaround

No workaround, besides upgrading Confluence to at least 7.2.0