Hi @Anonymous ,
Do you use the HTML text control to display the multiple line text type column value from your SP list?
Have you enabled "Auto height" proeprty for the HTML text control?
I have made a test on my side, and don't have the issue that you mentioned. The HTML text control display the Multiple line text well.
Please consider take a try to turn off/disable the "Improved app rendering (final validation)" option within Advanced settings of App settings of your app, then re-publish your app, check if the issue is solved.
If the issue still exists, please consider take a try to add a Rich Text Editor control within your app to display the Mutiple line text instead of Html Text control. Then check if the issue has been fixed.
Best regards,