Earlier this week Merthyr Tydfil had the highest weekly infection rate in the UK.
Officers attended the bonfire to provide "suitable advice" and Welsh Government Covid rules.
By Ben Price
A woman who lost an eye after being hit by at firework warns over lockdown bonfire parties.
By Lucy Ballinger & Alex Jennings
BBC Wales Live
The justice system needs investment to end a backlog of Covid-related court delays, a police chief says.
Deborah Lamont's parents say nurses should have known she had previously attempted suicide.