I think you’re forgetting to consider a key piece of information. You have to take into consideration that anytime you exit incognito using an ERC-20 token or ETH, you are interacting with a smart contract. This is different from a regular txn (Wallet to wallet). This is the key difference .
You may have checked several other platforms but that is irrelevant unless you specifically checked the fee to interact with a smart contract from these other platforms as well.
Again, gas fees are dependent on the complexity of the transaction and the operations incurred by the transaction.