What TSV is
TSV is CSV with tabs instead of commas. Because tabs almost never appear inside a value, quoting is rarely needed and the files are easier to read by eye.
Bioinformatics, log processing, and anyone who has copied a block of cells out of a spreadsheet: the clipboard format is TSV.
What JPEG is
A lossy image format designed for photographs, where losing a little detail in a gradient is invisible.
Places that will not accept a PNG upload.
What changes when you convert TSV to JPEG
The tab is unambiguous, so there is no delimiter to guess. This is the most reliable of the delimited formats to read.
The same render as PNG, saved as JPEG. It is the worse choice for a table and it is worth knowing why: JPEG compresses by discarding detail around sharp edges, and a table is nothing but sharp edges. Letters get a visible halo and hairline rules blur. It also has no transparency, so a background colour is always painted rather than left clear.
What carries over from TSV to JPEG
TSV records 3 things about a table that JPEG has no way to hold.
Nothing in JPEG records that the first row is a header. It is drawn at the top and looks like one, which is all that is left of the distinction.
TSV can be read one record at a time. JPEG has to be complete before it means anything, so the whole table is held in memory while it is written and a file that gets cut off part way through is not partly usable - it is unusable.
JPEG is the end of the line for this data. Reading the table back out of it is a separate and much harder problem than writing it, so keep the TSV if you will need the values again.