The wobble that shows up after a floor job
If you just had new tile, vinyl plank, or laminate put down in the bathroom and the toilet feels a little different now, rocking slightly when you sit, or the caulk line at the base cracking within a few weeks, you're not imagining it. Adding a new floor almost always changes the height of the flange relative to the floor surface, and that little bit of change matters more than most people expect.
In a lot of Nixa homes, especially the ranch-style houses built in the 70s and 80s around the older parts of town, and the slab-on-grade builds that have gone up more recently near Highway 14 and out toward Christian County, bathrooms were finished with one layer of flooring and never touched again until now. When a new floor goes in on top of the old one, or the old floor gets torn out and replaced with something a different thickness, the flange that used to sit flush or slightly proud of the floor can end up buried or, less often, sitting too high.
Why this matters more here than it might seem
Southwest Missouri gets real humidity swings, wet springs, dry late summers, and a freeze-thaw cycle in winter that isn't as brutal as farther north but is enough to make houses shift a little every year. Slab foundations common in the area move slightly with moisture in the clay-heavy soil around Nixa, and older pier-and-beam homes settle unevenly over decades. A flange that was fine when the house was built may already have been slightly off before anyone touched the floor. New flooring just exposes the problem or makes an existing gap worse.
More on this from Reading List Flange Height After A New Floor Goes In.
What a buried flange actually does
When the flange ends up below the new floor surface, the wax ring underneath has to stretch to make up the difference. Sometimes it does the job for a while. But a wax seal that's compressed unevenly or asked to bridge too much of a gap tends to fail early, and you don't always know it's failing until you see water staining on the ceiling below or notice a musty smell near the base of the toilet that wasn't there before.
A flange sitting too high causes a different problem. The toilet can't sit flat, so it rocks, and every time someone sits down or shifts their weight, the wax ring gets stressed at a different point. Over months that turns into a slow leak too, plus a toilet that never feels solid no matter how many times you tighten the bolts.
What you can check yourself
Pull the toilet, or ask whoever did the flooring to do it before they call the job finished. With the toilet off, look at how the flange lines up with the new floor surface. As a rough guide, the top of the flange should sit at or slightly above the finished floor, not buried under it and not perched an inch above it. If you can slide a piece of paper under the flange with room to spare, or if the flange sits noticeably below the tile or plank surface, that's your answer.
You can also check for looseness before you ever pull the toilet. Sit on it and shift your weight side to side. Any rocking, even slight, especially if it's new since the floor went in, points to a flange height mismatch rather than just loose bolts. Tightening the bolts on a toilet with a height problem usually just cracks the porcelain base eventually, so don't lean on that as a fix.
Where this stops being a DIY job
Extension rings and flange spacers exist for exactly this situation, and for a small height difference, maybe a quarter inch to a half inch, that's a reasonable fix. But stacking too many spacers, or using the wrong kind on an older cast iron or clay flange common in Nixa's older housing stock, creates a weak point that can crack later. If the flange itself is cracked, corroded, or was already a mismatched size before the floor work, that's not something to patch over with rings.
If you pull the toilet and find the flange sitting more than an inch off from where it needs to be, or if the subfloor around it feels soft or damp, stop there. Soft subfloor usually means water has already been getting in, and that's a repair job, not a shim job. A plumber can reset the flange at the correct height, which sometimes means cutting into the new floor slightly at the base, an unwelcome step but a cheaper one than dealing with a slow leak that's been running under the floor for a year.