Huh, I never see SDFs turn out that wiggly... then again, the SDF font I mainly test with (itim) doesn't have many straight edges, so the default settings I suggest might not be optimal for all fonts. Is it possible to use an SDF font generated by TMP with STM? I've never actually bothered to see if the systems are compatible, but now that TMP is included with Unity, that's an option to consider.
The SDF generator I suggest, from what I gather, should be the same code base as what TMP uses anyway? You might have to try upping the font quality even further, or making the inside/outside be larger or smaller (I can't think of which one would produce a sharper image)
I *do* see a small amount of that same "wobbliness" on the TMP text, so it's gotta just be the SDF generation, that's what I'm thinking anyway?
That's my best guess for now! Please give these ideas a shot!