I think if they reworked the matchmaking for online turf war, it would resolve a lot of problems.

Something like providing an option when searching for matches to prioritize similar skill level based on your turfing amount, kills and deaths in a match. I've heard it does something like that this now but it definitely doesn't seem like it from my experience and instead seems more like I'm playing the lottery whether I get paired with extremely new single digit players or high level S+ and X rank players regardless of how good or bad I play in matches.

Alternatively just doing level based matchmaking so that people who have spent similar amounts of time in the online mode, will be put in lobbies more frequently in turf war. Not fool proof since smurfs and Splatoon 1 veterans exist but I'd prefer it over how it is currently.