See "What is the ozone layer?"
The ozone layer consists of pool of ozone molecules. they are allotrope of oxygen molecule.
There would be less free oxygen, so there would be less ozone.
No oxygen is not a danger to ozone layer in stratosphere. It is because oxygen itself participates in the creation of ozone.
See "What would happen if the ozone layer vanished?"
Ozone is created by the oxygen molecules. When the UV falls on oxygen, ozone is formed.
Oxygen is O2. Ozone is O3.
Uranus does not have a ozone layer. It does not have a oxygen and no UV radiation to convert it into ozone.
The ozone layer is broken down by UV. It decomposes it into nascent oxygen and oxygen molecule.
Ozone layer is formed by UV radiations. These UV rays decompose oxygen to 2 nascent oxygen which reacts with oxygen to form ozone.
Ozone layer is made up of ozone. It is an allotrope of oxygen.
Oxygen diffuses in and out of the ozone layer, and ozone decays back to oxygen. So any oxygen lost is made up... usually from the troposphere (and its nearby plants).