Google sheets ArrayFormula with IMPORTRANGE always return same result
Try this:
=ARRAYFORMULA(
IFS(
ROW(L:L) = 1,
"Date",
K:K = "",,
True,
IFNA(VLOOKUP(
M:M,
{
SEQUENCE(ROWS(IMPORTRANGE("https://docs.google.com/spreadsheets/d/123456123456lkjjj", "Sheet1!D:D"))),
IMPORTRANGE("https://docs.google.com/spreadsheets/d/123456123456lkjjj", "Sheet1!D:D")
},
2,
))
)
)
IMPORTRANGE works once inside ARRAYFORMULA, so it is not possible to call it in a loop. But you can get everything with it and then loop through it.