IIRC the default setting on Handbrake does result in a fair bit of loss to the quality (it’s been a while since I’ve used it, and there’s likely been a few changes).
This article explains how to change the video quality so you won’t lose much - or any - quality in the video settings:-
(there may also be some decent youtube videos out there which may have more helpful info too)
I think I used to use a video setting on the RF scale of 12-14, though would have a play around with them to find the which setting gave the best / most acceptable results.
Good luck with it man.