On what basis did the Welsh Government decide that people singing in a church need to wear a mask when spectators in a sports venue do not?
The requirement to wear a face covering applies to all indoor public premises, except hospitality, which would include spectators in an indoor sports venue.
It is not a legal requirement to wear a face covering outdoors, which applies equally to worship and spectating. A specific coronavirus risk assessment should be carried out to determine what protective measures should be put in place, which might include face coverings.
The rationale for the use of face coverings in indoor public places other than hospitality settings was set out in the update to our Coronavirus Control Plan on 14 July.
https://gov.wales/coronavirus-control-plan-alert-level-0-zero
Since 11 October, and as an additional mitigation in response to an increase in the number of COVID-19 cases, people attending large sporting events in Wales have to prove they are either fully vaccinated or have had a negative test.