This Not a STO-3225A for sure .
How do you know?
Were did you fine the voltage for this ??
The information below the Taobao listing lists 3.3V as supply voltage (see one of my last posts).
Simple this is the Date code and country of origin why would any one remove the top line . !!
I would ask the supplier what was the number that has been removed
It was probably a L series the rest you have to guess .
Sorry .
Try running it at 1.8v and set your scope timebase so there is only 3 cycles and slowly increase the voltage on the vcc
What you are see is almost good , not knowing your setup and how you have set the scope .
It should be closer to a clipped sign
and see what happens . if it has a better resonance @ 1.8v or 3.3 v .. Give time for it to stabilize between each adjustment.
Not sure why you went for this tcxo there are so many really good New high quality tcxo's on the market
from reputable sources. with a spec sheet that matches . for a few $