In April 2024, the BLAST FASTA files in this directory will no longer be
available. You can easily generate FASTA files yourself from the formatted
BLAST databases by using the BLAST utility blastdbcmd that comes with the
standalone BLAST programs. See NCBI Insights for more details
https://ncbiinsights.ncbi.nlm.nih.gov/2024/01/25/blast-fasta-unavailable-on-ftp/