I will do my best to translate what I had to do to remediate:
1. Power Platform admin center. Select environment
2. Resources - All Legacy Settings
3. Customization
3. Expand Entities
4. Scroll down to 'Transaction' - Click Forms
5. Click on Active Form - Fundraising:Transaction
6. Select Form Properties
7. Repeat on Active Form - Transaction
I did not document the scripts I was told to delete, but I can tell you neither form has any scripts OnLoad or OnSave