Yes. A criminal record can affect UK ETA approval.
During the UK ETA application process, you may be asked questions related to criminal history, and the decision may depend on the nature and details of the record.
Having a criminal record does not mean every case will be treated the same way. However, depending on the details, a UK ETA may be refused, and another type of permission, such as a Standard Visitor visa, may be required instead.
The most important thing is to answer the application questions accurately. If you have a criminal record but provide incorrect information or leave out relevant details, it may cause issues with your UK ETA approval, travel procedures, or entry checks. Before applying, check your situation carefully and enter the information accurately.