en.wikipedia.org
"
The original FreeSync is based over
DisplayPort 1.2a, using an optional feature
VESA terms
Adaptive-Sync.
[5] This feature was in turn ported by AMD from a Panel-Self-Refresh (PSR) feature from Embedded DisplayPort 1.0,
[6] which allows panels to control its own refreshing intended for power-saving on laptops.
[7] AMD FreeSync is therefore a hardware–software solution that uses publicly-available protocols to enable smooth, tearing-free and low-latency gameplay.
FreeSync has also been implemented over
HDMI 1.2+ as a protocol extension. HDMI 2.1+ has its own variable refresh rate system.
[8]"
So what if its based on that?
What matters is that it does the same and its cheaper and an open standard....