In my case its an issue because I have a monitor with only a single DP port and I need to switch between my tower and laptop. I have to use HDMI for the laptop to monitor connection.
The Synaptics VMM7100-based adapters only support VRR on older firmware versions with bugs.
The Chrontel CH7218 is the most reliable but still also suffers blackouts during VRR.
ParadeTech PS196 adapters advertise VRR support but their DPCD does not correctly communicate that it is supported. So even if you add the chip to the VRR PCON list in the amdgpu driver, it still won't see VRR as supported.
And while some of these advertise themselves as displayport 2.0, all of them only support bandwidth of 25.96gbps on the displayport side, requiring DSC for 4k 120hz 10bit color, even though they support 48gbps on the HDMI output.
I've owned 2 of these (returned and reordered thinking the first might've just been bad) and neither worked properly on Linux with an AMD 9070xt and an LG CX. They'd have black screen dropouts every few minutes, and occasionally full screen color corruption.
They have limitations, specially when driven to the limits of the specifications.
When doing 4k@120fps 4:4:4 chroma you might have to deal with longer handshakes and sometimes even no handshake at all. Or random dropouts. Or HDR not activating properly.
There are only a few adapters that support the 2.1 features (hdr+vrr+high resolution+high refresh rate, no lossy DSC). I even had to flash custom firmware for most of those features to work (vrr still doesnt)