Which is the fee spent on the transfer? How to get the fee_used?

[LXHLeaner]

Problem: The handling fee deducted from my account is "fee": "2906481685620092",but the "fee_used": is "3626624538723810", Which one should I believe, fee or fee_used? What is the fee_used meaning? How to get it?
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link: https://astar.subscan.io/extrinsic/0x09754fd0064edf2228a3cc5e0a71db05674b1bba85570031bd823e813beb6cd6
Chain: ASTAR
Block Hash: 0xce29231bc5ca9b6ccdd464b6792ddd66bffd802237ffc21b858938ddd64f62a5
Block Number: 2444067
Hash: 0x09754fd0064edf2228a3cc5e0a71db05674b1bba85570031bd823e813beb6cd6
"fee": "2906481685620092",
"fee_used": "3626624538723810",