Yes. The usual fix is flat-field correction: make a reference scan of a uniform target, then use it to normalize your negative scans.

A plain empty scan may work if it gives a smooth brightness map, but a scan of a uniformly lit gray target is often better because it avoids clipping in the brightest areas. You may want to try a few exposures and choose one that is not saturated.

In GIMP, place the reference image as a layer and use Divide mode, or otherwise divide the scanned negative by the reference image. This compensates for the scanner’s uneven illumination. A little smoothing/blur on the reference image may help if the pattern is noisy.

After correction, invert the negative as usual. If possible, work in 16-bit to reduce rounding/posterization, then export to your preferred archival format afterward.

This can improve the result, but it won’t recover detail already lost to poor scanning or clipped tones. If the scanner is badly uneven, rescanning on a better scanner may still be the best solution.