We always encode tags in case of Prefix tree now and so the code path, while decoding, not checking what is there in FileInfo. So functionally no issues now.
If we do
HBASE-10453 this change will be very important to make sure BC for old files.
We use the file info MAX_TAGS_LEN to know the presence of tags in a file. In case of prefix tree we always have tags in files even if all kvs have 0 tags. So better we can add this file info into prefix tree encoded HFiles. Now it get missed.