Can you post the exact Gigabyte B450 Motherboard you have. The Ryzen 3600 should support fTPM. I have a Ryzen 3700X that I now have fTPM enabled to be able to upgrade to Windows 11.
My Asus Motherboard has a TPM Header on it which means it either accepts software fTPM or hardware TPM Module.
After I enabled fTPM in BIOS I then went into Windows Settings to verify that TPM has been enabled even though I don't have any hardware that needs TPM enabled.
According to this tech site concerning TPM supported Motherboards: https://www.digitaltrends.com/computing/motherboards-that-support-tpm-windows-11/
To verify if your Motherboard supports TPM go to your Motherboard's Specs support page.
This previous LinusTech Forum User is having the same or similar problem with enabling fTMP on his Ryzen 3600 processor: https://linustechtips.com/topic/1387054-tpm-20-will-not-turn-on-ryzen-5-3600/
Make sure you have BIOS set in UEFI Mode.