Take note that it's possible that a service doesn't allow you to make withdrawal to a certain type of address, but it's not possible that a service doesn't accept deposit from a certain type of address.
As mentioned above by Charles-Tim, you can send bitcoin from any type of address to any type of address.
But those two exchanges give you a choice to receive in Taproot address, which could be cheaper it terms of fees than send to native segwit or other types.
Sending to taproot addresses is not cheaper.
With any taproot output you add to your transaction, you increase the virtual size of the transaction by 43 vbyte.
That's 31 vbyte for a native segwit ouput, 32 vbyte for nested a segwit output and 34 vbyte for a legacy output.
More information on the topic created by Charles-Tim:
Pay-to-taproot (P2TR) transaction fee