Since this happened on two different Motherboards seems like you received a defective CPU.
Open an online AMD Warranty Request and see if they need you to RMA your processor for a replacement from here: https://www.amd.com/en/support/kb/warranty-information/rma-form
The Asus motherboard requires BIOS version 0602 to be installed to recognize your Ryzen 9 3650 processor: TUF GAMING X570-PLUS (WI-FI) CPU Support | Motherboards | ASUS USA
In fact your motherboard supports that processor with the original BIOS version which is 0602.
The MSI Motherboard supports your Ryzen 9 with the following BIOS version or later: Support For MPG X570 GAMING EDGE WIFI | Motherboard - The world leader in motherboard design | MSI G...
Like Asus BIOS version MSI BIOS version that supports your processor is the Original BIOS version of the motherboard.
So this also is a good indication you have a defective processor.
NOTE: Make sure you processor is not physically damaged like with bent or broken pins which is not covered by AMD Warranty.