News on ecommercebytes indicates eBay will begin charging their Final Value Fee on the total transaction amount (sale price plus shipping plus sales taxes) instead of the final value fee on the sale & shipping plus a payment processing fee. The changes will effect those in Managed Payments which will include most sellers sortly.

Here's a link to the article
https://www.ecommercebytes.com/C/blog/blog.pl?/pl/2020/5/1588884404.html