Most medium format sensor lacks antialias filters to provide more pixel-peep micro contrast at the cost of having false colors and moiré. Fabrics is worst case.
You can remove it (or rather hide it) with software, but the result will be worse than it had been with a proper antialias filter on the sensor. The other alternative is to shoot less sharp pictures by having a smaller aperture or shoot slightly out of focus.
Yes, being without antialias filter is bad, but MF sells a lot on resolution and being without it gives a pixelpeep advantage and as we all love to pixelpeep (but rarely admit it) being without AA filter is generally seen as a "feature" rather than the bug it is. Be glad that you don't have a 22 megapixel sensor, it would be even worse on that