From my experience, playing since 0.4, most quitters are people who lost it to grind strain, gear fear stress overload and lack of play/load/grind ratio, such as spending most of playing time surviving through first tasks, trying to get to opening the flea market, post-wipe/post-break learning curve or similar stuff that are not playing, having tarkov 'fun' (after all, tarkov is an abusive relationship you love) or just casually grinding up/improving hideouts and gear levels.
(Side note: everyone I know on Tarkov is a full time worker/student (at least 9 hours a day for both) like myself which means we don't have that much hours a week on Tarkov as the average younger gamer.)
From my understanding, and correct me if I'm wrong, tarkov arena will be a faster-paced mod than the usual EFT. The recent teaser suggests several characters to choose from but I'm not a big expert on the details yet.
Recently I found out about a new mod for "new players" on rainbow six siege which is a fast-paced-quick-respawn deathmatch that lets you improve gun-play, training on aiming at real players with minimal loading times or bs times such as rounds, character choosing, rematches etc.
I think that if Arena introduces a similar mode that will allow players to dive in relatively quickly, fight against real PMC movements to improve aim and tactics for both sides with minimal loading times and especially quicker respawns, Tarkov could win back a shit load of it's player base that has just gone tired from all I mentioned above and more.
That, of course, putting cheaters, stability and optimization aside for this post.