It has absolutely no bearing on the finished epub. That much is easy.
I would suspect the difference between machines is a Qt5 version issue. You were using Linux if I recall correctly? Are both of the machines running Linux? The same flavor of Linux? The same Desktop Environment? The same fonts chosen for the text in Code View? Both fully updated, and with the same versions of Qt5?
If the answer to any of the above questions is no. Then there's probably very little to be done. Sorry. Qt do what it do.
There's also the issue of various font-config tweaks to improve font rendering on Linux that may play a role on one or the other machine.