Hi @Moksha,
When using a lot of formulas that loop through your datasource (filter, addcolumns, showcolumns, lookup...) Power Apps sometimes gets confused what 'ThisRecord' actually refers to. In this case, we can explicitly tell Power Apps what record we want to refer to.
Would it be possible to add the following changes to your code:
(1) At the end of your filter statement write 'As Main'
//Your code...
'Work Item Status'<>"Closed") As Main,
//Your code...
(2) Swap the code for your textSearch with:
//Your code here...
"TestSearch", Text(Main.'Request Number')),
//Your code here...
If this solves your question, would you be so kind as to accept it as a solution.
Thanks!