How to Repeat Transposing A Query Output matching values from a range reference over the whole column in Google Sheets?

Question

I need to transpose column B values where column A values are matching over the entire column.

I tested this but it's not working:

=transpose(QUERY(A2:B,"select Col2 WHERE Col1 MATCHES '"&A2:A&"' "))

Current output:

Item 1	Item 2	Item 3	Item 4	Item 5
7	A1	A1	A2	A3
7	A2
7	A3
8	b1
8	b2
8	b3
9	c1
9	c2
9	c3
9	c4

Needed Output:

Item 1	Item 2	Item 3	Item 4	Item 5	Item 6
7	A1	A1	A2	A3
7	A2	b1	b2	b3
7	A3	c1	c2	c3	c4
8	b1
8	b2
8	b3
9	c1
9	c2
9	c3
9	c4

Answer 1

Here's one approach you may test out:

=reduce(tocol(,1),unique(tocol(A2:A,1)),lambda(a,c,ifna(vstack(a,torow(filter(B:B,A:A=c))))))