As per FX3 datasheet, Vih/Vil depends on the Clock supply voltage. CVDDQ.
it could be 1.8V or 3.3V
If CVVDQ is 1.8V, then VIH min is CVVDQ-0.4V which is 1.4V
VIH max is CVDDQ+0.3V which is 1.7V
If CVDDQ is 3.3V, then VIH min is CVVDQ*0.625 which is 2.0625V
VIH max is CVVD+0.3 which is 3.6V
VIL min is -0.3V , VIL max is CVVDQ*0.25 which is 0.825
we will confirm the answer with the designers and update you back.
Datasheet link below.
Table 8 - DC Specifications has the details.