(newbie) Problems with shading under a transparent layer

[rizzling]

Hey guys, I have created a animation of a card in a transparent glass box/frame. I am running into problems with the shading. The rendered result doesn’t look as clear/sharp as I want it to be. Unfortunately I only have a bad setup atm with which I am forced to work on. So I need to use a renderfarm even for single frame to preview, yeah it’s horrible…But after about 10 tries to fix the shading/resolution in the rendered result (what took me hours) I think it’s the best idea to ask here for some help hehe
Here my .blender with the image in a .zip: https://www.transfernow.net/dl/202307155ldtRgrT

I have not that much experience with blender so I guess there are some basic node settings I have done wrong and the scene lights might be a problem too I sm not sure about it :/

Thanks everyone in advance for any help with this!

Ps: I use blender 2.95.3 and fox render farm