BLAST SEG masking

It is a little known fact that NCBI BLAST in blastp mode applies SEG low complexity masking to the target sequences by default. I asked GPT 5.5, Opus 4.8, Gemini and Groq about this and they all told me no!

Lessons learned: Things can happen inside bioinformatics tools that are not written in any paper or any documentation or anywhere. Sometimes the developer is the only person in the world who knows about them. Respect the people that understand the tools that billions of dollars worth' of science are being built on top of.