HI Sam @AngelAzrael ,
Hard to say.
Maybe turn down your World Lighting to 0 and see what happens (the Environment Lighting doesn’t cause Caustics and might ruin the visibility of the Caustics if it’s relatively strong).
Also, make sure that the glass Objects and the backdrop have Shadow Caustics enabled in the Object Properties and the Light in the Object Data Properties.
The glass Objects also shouldn’t be set to Shade Flat.
That’s all I can think of at the moment.
