The bulge at the base has one of three specific causes
Elephant foot, a visible outward bulge at the very bottom of a print, comes from the base layers spreading wider than intended, and it is almost always one of three specific things: the first layer got physically squished too flat (Z-offset too low), the bed ran hot enough to soften the base of the part as it printed, or the slicer has no elephant-foot compensation configured to counteract either effect. This tool separates those three causes and protects a fit-critical base dimension specifically when it matters.
How the triage works
A visibly squished first layer weighs heavily toward Z-offset. A bed temperature suspected too hot for the material weighs toward thermal spread. If neither is suspected, the default hypothesis becomes simply not having compensation configured at all, since that is the most common gap once the two physical causes are ruled out. A noticeable (versus slight) bulge adds weight to both physical-cause hypotheses, since a bigger bulge usually means a bigger underlying cause.
Worked example
A slight bulge, first layer visibly squished, bed temperature not suspected, fit-critical base: the tool ranks Z-offset as the top hypothesis and recommends a first-layer squish test, then explicitly flags that since this base needs to mate with another part, the fix should be verified by measuring the actual result, not just assumed to have worked.
A common mistake
A frequent error is fixing Z-offset or bed temperature but never actually measuring the base afterward to confirm the bulge is gone. A visual "looks better" check is not the same as a caliper measurement, and for a fit-critical base, the difference between those two matters. Confirm the fix numerically, not just by eye, before printing the full production run.
Limitations
This tool ranks plausible causes from the symptoms you described. It cannot measure your actual Z-offset or bed temperature, so treat the ranked list as a place to start testing, not a confirmed root cause. For a fit-critical base, always measure the actual result rather than assuming a fix worked.