Question on the precedence of AND OR operator

Dear experts,

I have this query which involved "AND" and "OR" operators. For the operation which are in bold, they return different results when I changed its order.

I have share the following scenario and their results. Could anyone please advise how could this happens? Thanks.

Work Fine: --23178 rows

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select count(*)

  from test_table

  where 1=1

   AND (LAST_REPORT_TIME BETWEEN TO_DATE(:DATE_FROM,'DD-MON-YY') AND (TO_DATE(:DATE_TO,'DD-MON-YY') + 1))

  AND (EXCLUDE_FLAG = :EXCLUSIONS OR NVL(EXCLUDE_FLAG,'N') = 'N') ;

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Return 0 records:

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select count(*)

  from test_table

  where 1=1

  AND (EXCLUDE_FLAG = :EXCLUSIONS OR NVL(EXCLUDE_FLAG,'N') = 'N')