In short, there is no bug, that text is just encoded with
chunks.
Checked with Fiddler, created raw HTTP request and response is same as in GLBasic, one of headers is: 'Transfer-Encoding: chunked', and as I assume GLB doesn't support such decoding (same with comperssion for response body) and it passes raw response body to you, so check your php code what headers are you setting, or force no encoding/compressing for that particular highscore file.
ps. in browser it will look ok as you don't see raw headers and all browser support encoding / compression.