You’re not missing anything. This is basically how Wizz Air (and a lot of low cost airlines) work.
The change fee is fixed and doesn’t care how cheap the new flight is. So even if the ticket itself is 22 euro, you still pay the 45 euro change fee on top of any fare difference. That’s why buying a brand new ticket is often cheaper.
They price it this way on purpose. It pushes people to commit or just rebook instead of changing.
If you don’t need the original return anymore, the usual move is to just eat the first ticket and buy the new cheap one.
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