It’s similar to exchanging one stable coin for another in the eyes of the IRS. Even when both stable coins are $1 or 1 to 1. I would say you still have to track the cost basis like you do with stable coins. The difference with a coin that moves in value is that you are going to trigger a taxable event. For example, if you bought your BTC for 48,500.15 then converted it to wBTC for 48,500.15 you would have no taxable event as it’s the same price. However for example, if you bought BTC at 48,500.15 and converted it later to wBTC at 51,810.50 you would end up with a taxable event of 3,310.35 since the price of Bitcoin moved up. On the plus side, it may also trigger losses if the price of Bitcoin went down, which you could claim.
This is basically how I see it getting taxed and how the current tax code is written. I don’t see it being safe to do it the other way as I don’t think it follows the IRS tax codes. The only way that changes is if the IRS clarifies differently how DeFi tokens are taxed. Or creates a new law where swapping the wrapped tokens in the DeFi space doesn’t trigger a taxable event.
What I think you are confusing this with is in regards to Token Swaps. This would only happen in cases like where EOS ERC-20 token was swapped for mainnet coins and the ERC-20 token was deprecated. In this case, it would be treated like what happens when your stock goes through a merger or acquisition, in which you end up with new shares of something else. The IRS does not look at the event as a taxable transaction cost basis from old shares carry over to the new ones.