I think often the gaslighter is also trying to convince the victim, and others of a version of events that paints then more favourably, often they end up believing their own version of events, which makes them incredibly convincing
MIL and DH have very poor episodic memories and have a tendency to do this. I once heard a story at end FIL told me I'd been there - MIL had obviously forgotten but it bore no relation to event bar one thing and MIL looked way better.
It's very easy to be in the wrong though - if you correct them oh you always have to be right if you don't what they say can become accepted wisdom and if it’s ever questioned it’s your fault.
I also wonder how much manipulative – some I think is.
DH also started fact checking me not all the time but frequently enough I notice – magazine we get had question section he’s queried facts I’ve know - he checks on-line occasionally demands a source – I never hear when I’m right only when wrong – I saw the magazine and I was right and he brushed it off when I asked why. I do think I'm starting to talk less and self censor more though I'm hoping he'll stop doing it.
I grew up in a family where I couldn’t know anything, I got quiet, read a lot retreated - I seem to be doing a mix of arguing and that. It’s corrosive to confidence but also, I think affection.