Unstable Teleportatium is a less predictable form of regular Teleportatium. It can be difficult to tell that Teleportatium behaves predictably at all, which is probably why you're having trouble noticing a difference.
When stained by "stable" Teleportatium, you will teleport a relatively set distance1 at random intervals in the direction you are facing2. This makes it useful for bypassing obstacles that you can't or don't want to dig through. In comparison, Unstable Teleportatium teleports you a random distance, at random intervals, in a random direction. This effect may be useful for escaping a dangerous foe, but it's just as likely to end you up in a worse situation (such as surrounded by enemies, or submerged in lava) unless you know everything around you is safe for a substantial distance. Still, if you feel safe taking a chance or if you're immune to most hazards through perks, you might find this a worthwhile gamble.
Note that you can turn ordinary Teleportatium into its unstable variant by mixing it with whiskey. The opposite transformation (unstable into stable) is done by mixing Unstable Teleporatium with slime.
1: Subject to rules about ending up inside terrain which I'm not fully familiar with. In my experience, objects that are inside terrain tend to instantly zip to the first open space above their position.
2: As far as I can tell this is based on the direction your mouse is pointing, but I haven't fully tested it.
I've only seen Unstable Polymorphine once. From the limited testing I was able to do, it seems like it can only transform you into Hiisi enemies. A recent Reddit thread I found concurs.
Unstable Polymorphine can be created by combining Flummoxium, blood, and oil. It can also be found naturally (but rarely) in
the Ancient Laboratory.
Unlike Unstable Teleportatium, when I combined Unstable Polymorphine and slime, it did not create the stable Polymorphine variant; the two liquids just sat side by side.