Insert a Blank Row After Every Change of Product

Let’s do it step by step :

1- =SEQUENCE(ROWS(B4:E13))

2- =B4:B13=B5:B13

3- =DROP(H4#,-1)

Which is  :  =DROP(B4:B13=B5:B13,-1)

4-  =I4#*1

Which is  : =DROP(B4:B13=B5:B13,-1)*1

5-  =VSTACK(1,J4#)

Which is : =VSTACK(1,DROP(B4:B13=B5:B13,-1)*1)

6-  =FILTER(G4#,K4#=0)

Which is  : =FILTER(SEQUENCE(ROWS(B4:E13)),VSTACK(1,DROP(B4:B13=B5:B13,-1)*1)=0)

7-  =HSTACK(G4#,B4:E13)

Which is : =HSTACK(SEQUENCE(ROWS(B4:E13)),B4:E13)

8-  =IFNA(VSTACK(L4#,M4#),"")

Which is : =IFNA(VSTACK(FILTER(SEQUENCE(ROWS(B4:E13)),VSTACK(1,DROP(B4:B13=B5:B13,-1)*1)=0),HSTACK(SEQUENCE(ROWS(B4:E13)),B4:E13)),"")

9-  =SORT(C18#,1,1)

Which is :  =SORT(IFNA(VSTACK(FILTER(SEQUENCE(ROWS(B4:E13)),VSTACK(1,DROP(B4:B13=B5:B13,-1)*1)=0),HSTACK(SEQUENCE(ROWS(B4:E13)),B4:E13)),""),1,1)

10-  =DROP(I18#,,1)

Which is :

=DROP(SORT(IFNA(VSTACK(FILTER(SEQUENCE(ROWS(B4:E13)),VSTACK(1,DROP(B4:B13=B5:B13,-1)*1)=0),HSTACK(SEQUENCE(ROWS(B4:E13)),B4:E13)),""),1,1),,1)

<< In one formula :>>

 =LET(

    a, B4:E13,

    b, TAKE(a, , 1),

    c, SEQUENCE(ROWS(a)),

    DROP(

        SORT(

            IFNA(

                VSTACK(

                    FILTER(

                        c,

                        VSTACK(1, DROP(b = DROP(b, 1), -1) * 1) = 0

                    ), HSTACK(c, a) ), ), 1, 1), , 1))