TMP20: we bought part#TMP20AIDCKR, during QC inspection, observed discoloration on leads

Part Number: TMP20

we bought part#TMP20AIDCKR, when our QC team do inspection, there are observed discoloration on leads, details as below pictures, we have concern that if it's ok on the board. pls kindly help review and advise if it's normal, thanks!