Well, it is in the human's nature to group up to increase chances of survival. So why do you think it's unexpected, bad or against the rules to see this in a survival BR? I'm even guessing that's how Apex game came to life as a squad based BR, to make teaming up official. Also, I'd say that teaming up without the ping system, revival or respawning and with "friendly" fire is really commendable, it takes extra effort to make it work and I've seen a lot of solo players wiping entire squads in team mode, they should have easier times with the unofficial teams from solo mode.
You guys asked for solo mode battle royale, but didn't say that you actually wanted 1v1 fights/tournaments, so...