Mangaplus has IDs for chapters in the URL. Usually they put up the IDs for the next 3-4 issues of Weekly Shounen Jump at a time. For example this week, the One Piece chapter has the ID 7479 at the end of the URL. The next 3 IDs 7480-7482 will be filled with the next three chapters of One Piece. The ID 7483 is the current chapter of Jujutsu Kaisen.
However if a manga has less than 4 IDs, it means it will be absent in at least one of the next 4 issues. So it will either go on break or it will end in less than 4 chapters. Since new manga pretty much never go on break, it's usually always cancellation.
Here's the Mangaplus IDs for the next month:
7310-7312 MHA (still using old IDs because of unexpected breaks, current chapter is 7311)
7479-7482 One Piece
7483-7486 Jujutsu Kaisen
7487-7488 (either MHA or new series replacing Mitama)
7489-7492 Black Clover
7493-7494 (either MHA or new series replacing Mitama)
7495-7498 We Never Learn
7499-7502 Dr. Stone
7503-7506 Act-Age
7507-7510 Chainsaw Man
7511-7514 Mission Yozakura Family
7515-7516 Mitama Security (only 2 IDs)
7517-7520 Agravity Boys
7521-7524 Undead Unluck
7525-7528 Mashle
7529-7532 Moriking
7533-7535 Bone Collection (only 3 IDs)
7536-7539 Time Paradox Ghostwriter
7540-7543 Ayakashi Triangle
7544-7547 Magu-chan
7548 (probably a new series replacing Bone Collection)
7549-7552 Hardboiled Cop and Dolphin
7553-7556 Me & Roboco
As you can see, every single manga has enough ID spots for 4 chapters in total (this weeks chapters included), except for Mitama Security and Bone Collection. So this means, Mitama Security only has one chapter left next week and Bone Collection has two chapters left after the one that released today.
Usually it's pretty easy to tell whether a series will get cancelled or be on break. For example when an established series is missing an ID, it's usually because of a break, unless the manga is known to be in its final arc. If it's a new series that isn't doing well, it's pretty much always an axe.
This has so far been very consistent and users on the Mangahelpers forums have been using this trick since at least last year to find out earlier whether a series will end or not. Afaik, it has been 100% accurate so far. I didn't really find out about them until Guardian of the Witch ended. But it ended exactly in the issue where the last ID was filled. I also looked up an old post from last year where The Last Saiyuki ended in the exact issue where its last ID was filled.