Technically, IMpb labels are to be black on white IIRC, but pretty much no one but super fussy PO worker with issues will care in practice as long as it is readable.
The potential problem could be the tracking barcode and the 2d barcode at top being machine readable - no way to know.
Inking in the label text is probably not a good idea - might make it look like an attempted forgery, and odds of you being able to get the tracking barcode line widths correct is low unless you are extremely careful (the line widths are critical parts of the encoding).
The shipping label date is again technically to be observed, but in practice doesn't matter except to PO employees with axes to grind. (the machines don't care)
If you don't have to ship today to meet eBay handling time, I'd wait if you can get ink tomorrow and print another label.
Note that you only have 24 hours to reprint an eBay (or PayPal?) label. If you can do a reprint label now to a PDF file, you could print that tomorrow or whenever you have ink, otherwise you will need to print a new label tomorrow if the 24 hours is up (and void this one - you have 5 days to void)
It's your call on how dark the blue print is and guess at how readable the label is, and which way to go. If it makes it past humans and machines can read it then all good.
If an automated scanner somewhere along the way can't read the barcode, it could get misrouted and delayed or lost until a human intervenes.
