More Input-Values than necessary. How and why is this possible? No it is not the fees! The TXID I am talking about: 21179a8560a0a0906f0c3396af338f74528130d46b65b7f0c79c378d343b3177

blockchain.com link: https://www.blockchain.com/btc/tx/21179a8560a0a0906f0c3396af338f74528130d46b65b7f0c79c378d343b3177

3JZq4atUahhuA9rLhXLMhhTo133J9rF97j is a known Exchange-Address. 

Within above listed transaction there are multiple output-transactions which this address has received referenced as input-transaction to pay 1Kr6QSydW9bFQG1mXiPNNu6WpJGmUa9i1g.

In the above transaction, the source address 3JZq4a.. issues 7 previously received transactions to pay the target address 1Kr6QSy... with 2000 BTC, the rest goes back to its Change address.

My question now is why 7 transactions are "consumed" for this, when it would have worked with a fraction of the transactions.
For example the 7793.90573 BTC transaction.

My first assumption was that this is somehow chronologically handled by the wallet, but even if that were the case, according to the listing in the blockchain explorer after the first 4 referenced transactions used as input, the sum would be sufficient.

131,37735 BTC

1687,1255 BTC

157,79525 BTC

395,876 BTC

Are the first Transactions consumed and the result already exceeds 2k BTC.

I am thankful for any help and ideas!
Only the exchange can answer this - most exchanges and hosted wallets implement their own utxo handling mechanisms, and don't necessarily follow a space/fee optimal approach. There could be other considerations, such as reducing the number of utxos in their wallet, consolidating funds into bigger utxos during a low fee period as they expect larger payments during a high-fee time, or other business reasons.

Alternatively, it could just be an inefficient implementation.