# gzip dump and put it in the same directory as the backup
gzip dump.sql
# copy backup file to fixed-* , replace this with your own backup file name
cp backupfilename-2020-08-30-123456-v20200830123456.tar.gz fixed-backupfilename-2020-08-30-123456-v20200830123456.tar.gz
# decompress
gzip -d fixed-backupfilename-2020-08-30-123456-v20200830123456.tar.gz
# remove original dump.sql.gz from the archive.
# Note that the backup filename does not contain .gz in this step.
tar f fixed-backupfilename-2020-08-30-123456-v20200830123456.tar --delete dump.sql.gz
# add new dump.sql.gz. Note that the backup filename does not contain .gz in this step.
tar fr fixed-backupfilename-2020-08-30-123456-v20200830123456.tar dump.sql.gz
# compress it again. Note that the backup filename does not contain .gz in this step.
gzip fixed-backupfilename-2020-08-30-123456-v20200830123456.tar