Logic Masters Deutschland e.V.

Previous Dutch Flat Mate Puzzles
This has been a weekly series since '18 Oct 23'. Here is a spreadsheet link for all the previous puzzles in the series, which also has a few teasers for upcoming constraints/guest setters in the series (subject to change).

This alternative link offers a limited LMD search for Dutch Flat Mates.

Special Thanks
I first became aware of this constraint from a GAS puzzle, but when I opened a more challenging puzzle with this constraint using the LMD tags, I couldn't make any progress and eventually realised the original (non-GAS) 'Three is a Crowd' rule was more complex. The 'Dutch Flat Mates' series began as a vessel to force me to learn setting with new constraints. This constraint is the epitome of that, and setting this puzzle was an educational journey.
Huge thanks to the YouTube channel 'Unshackling Sudokus and Puzzles', for providing great Sudoku resources, including one for this contraint: Become a Master at Three is a Crowd Sudoku.

To play the puzzle, please click the image:

Initial Setter Difficulty: 3-3.5 / 5

Normal Sudoku rules apply
Place the digits 1-9 so that they do not repeat in any row, column, or 3x3 box.

Dutch Flats
Every 5 in the grid must have a '1' directly above it or a '9' directly below it. It may have both, but it doesn't need both.

Three is a Crowd
Clues outside the grid show the three numbers that have to be placed in the first three cells from that side. However, exactly one digit of each triplet is wrong. On each side of the grid (top, bottom, left, right) all of the wrong clues are different (example, if the wrong digit in Column 1 is proven to be 2, then 2 cannot be wrong again amongst the clues at the top of the grid).

Hint to start

The negative constraint on each side of the grid is huge for this constraint, I recommend watching the video linked above for Three is a Crowd help.
In the three '159' clues at the bottom, a different digit must be missing each time by the rules.
How are Flat Mates impacted with the '159' clue at the bottom that is missing a 5?

A little bit more info

The '159' clue missing a 5 has tension in the Column and in the box.
Where are 5 in Row 6 and Row 7, and how does this impact the Row 6 '159' clue?

Guest Setters
This time next week, I will hopefully be in Lanzarote, so it seemed an appropriate time to schedule the guest puzzles, and that's also why you've had four in a row from me for the first time since January 2024.

Next week Prof. Dorlir returns, and is channeling his inner Sia with "The Greatest" Dutch Flat Mate.

Then aqjhs with an official debut to the series, although he is an established friend of the Flat Mates, including an excellent Secret Santa gift for me. They are bringing a Full Rank variant that I promise is far more approachable than you might think!