You are free to call Liverpool champions but it has not been official or certain yet because they are still 9 matches to play and anything can be possible. I doubt if there's any team that can try to challenge Liverpool again in the premier league because it almost over, the moment Arsenal loses 2-3 or draw and Liverpool wins then it will be official and Liverpool will be handed over the premier league trophy but for the main time it is not yet over untill it is over. And yes it has been a great season for Liverpool even though they fucked up in the EFL cup.
It is only mathematically not official. But when we look at it from a reasonable aspect, there is no title competition anymore. Liverpool will probably make it official when there are a few weeks left for the end.

Indeed! There is no team to stand and fight back against Liverpool. For example Arsenal, what will even they do right? Arteta is really unhappy with the recent point losses. But his hands are tied on one hand. The team have been struggling with injuries for quite a while. Saka's absence affected them deeply. They got more inconsistent. They could have still done something more if they had a reliable CF at least. But guess what? There is no such player.

This summer, Arteta's first target must be to sign a star striker no matter what.
I think I see some points in what you're trying to say, they've not been officially crowned Champions of this season but majority of all fingers are pointing at them to win it, Manchester City doesn't stand a chance they're almost very far from it, Arsenal on the other hand is not very serious to win the title so the competition is not very tough anymore moreover most of their players would get enough time to rest from the pressure of the Premier league, they'll come back fresh and fit after the break.
Also, Liverpool are out of other competitions, this is their only opportunity of winning a silverware this season they won't let it slide past them, they're not some club that bottles the league, they've gone this far and chances of them winning it is getting much higher by every fixture. Anyways, if Arteta is serious about winning the league next season, he'll focus on signing a top quality attacker and an upcoming youngster as backup striker.