I don't remember TBH, not pretending. I do remember that Marner was less than impressive in the playoffs and we lost to MTL which IMO was the low point for this core (Marner included) so I get people being pissed. I remember posting that we should consider major changes and I'd be interested in knowing what we could get for Marner in a trade but I also said I wouldn't move unless the return was massive and I honestly don't remember people saying "get rid of him".
As for late 2022, I don't know about smear campaign. There were some people freaking out about the slow start of not just Marner, but pretty much everyone except for JT but it was just noise so I think I mostly ignored it. Not gonna lie, I remember being quite worried myself at some point as the team was just awful but I never thought we'd miss the playoffs like many people were saying. And Marner's regular season point totals, that's something I've never cared much about anyway and I knew he'd have a bunch of points at the end of the season anyway, team's too talented to play like crap forever.
Cliff Notes: Maybe there was more hate for Marner than I remember, I think 6 monts + 2 months of smear campaign is overdoing it though. Also not sure smear campaign is the appropriate term - Marner and the team sucked for a while there, nothing wrong with saying so. JMHO.