Hi Joy Abaja,
Thank you for querying in this forum.
I went through the post carefully and also tested from my side. I created a new SharePoint list and created a Multiple lines of text column, enabled Append Changes to Existing Text. Then I exported the SharePoint list to Excel by clicking Export > Export to Excel from ribbon. I cannot reproduce the issue, the multiple lines of column shows all lines. Below is my test result:
When viewing in SharePoint online:
When the list is exported to Excel:
I do understand the issue affects your daily work and feel sorry about it. For troubleshooting, you may try following methods and check the outcome.
1.Try to use a different web browser(Chrome, Firefox, Edge) to access the SharePoint list, export SharePoint list to Excel and check the outcome.
2.In the same SharePoint list, create a new Multiple lines of text column and re-enter the long texts in the column. Export to Excel and check the outcome.
3.Create a new SharePoint list and test if issue still happens.
In the meantime, could you also confirm information below? This helps us better understand the scenario and help you troubleshoot the issue:
1.Does the issue happen in a specific list or specific SharePoint site?
2.Do other users in your organization has this issue?
Many thanks for your patience and effort. Have a great day!
Best Regards,
Tina