Yea, There is no hardware support for DX9 in 6000+ series AMD cards. They use some emulation on the driver level to allow some level of functionality to still exist, but it is not performant.
Example comment chains regarding it:
https://forums.realflight.com/index....t-issue.55790/
https://forum.kw-studios.com/index.p...s-in-vr.18452/
https://community.amd.com/t5/drivers...mes/m-p/190547
Some discussions talk about disabling SMART ACCESS MEMORY :
https://community.amd.com/t5/general...-s/td-p/615342