A noisy switching regulator on the DC rail of your Low Noise Amplifier will modulate the amplifier's operating point and push noise and spurious content into your signal path. USB power supplies are particularly bad offenders.
If you are seeing a forest of spurs that do not correspond to any real signal, check your supply rail on an oscilloscope before you start suspecting your antenna or your filters. The problem is often on the bench, not in the air.
The fix is simple: replace the switching supply with a clean linear regulator that outputs on USB. A battery-backed power bank with a low-dropout linear regulator output, or a dedicated USB LDO supply or similar clean-rail products, will eliminate switching noise at the source.
The difference on the spectrum analyzer is immediate - the forest of spurs collapses to a flat noise floor with only your real signals remaining. For SDR setups in particular, a clean supply is one of the highest-return improvements you can make for the cost involved, often outperforming filter upgrades that address the symptom rather than the cause.