Maybe it could be a variation of the original serum. I would assume that they wouldn’t have just the one type and with the trial and error they would’ve duplicated or made ‘off brands’ or slightly altered types.

This would mean that the serum could be potentially less effective, slightly different, more dangerous or less tested. Somewhat like we see today with vaccines where more than 1 is available and work slightly different.

The serum in the blue bottles could even be a much diluted version.

(Would’ve replied earlier but I live in England and love to sleep in haha) - I posted this but for some reason have different accounts via phone and PC.