Dump your own cartridge using NXDumpTool to create a base XCI. Then use SAK (Switch Army Knife) to convert that XCI to a patched NSP yourself. This keeps your hands clean.
This video explains the impact of the unexpected GSP bug fix in the 13.0.3 update: super smash bros ultimate nsp patched
When you launch Super Smash Bros. Ultimate , it compiles a massive shader cache specific to your console's GPU. If your patched NSP is mismatched with your firmware even by one minor revision , the shader compiler triggers an "invalid instruction" error. Dump your own cartridge using NXDumpTool to create