especially an ultra widey!!
If you had to put up with any IQ losses due to filters, you need to make sure that the filter is at least producing a result that balances out the likelyhood that it will also degrade IQ.
At least with a CPL or grads or ND's or whatever other filter used for a specific purpose, you get some benefit in using it, so you weigh up the pros and cons and strike a balance.
UV filters serve no purpose.