How do I clean and remove grime on stained glass windows?

This article should help Chariss

https://blog.fantasticservices.com/how-to-clean-stained-glass-windows/

I don't know if it can be cleaned. To me it doesn't look like real stained glass. It looks more like faux stained glass made out of poured resin. Stained glass does not have fibers. Stained glass "came" looks like a train rail to hold the glass pieces in the grooves. It should be on both sides of the glass panel. You backside photo doesn't have this.

https://www.etsy.com/listing/130198824/stained-glass-tools-and-supplies-lead?gpla=1&gao=1&&utm_source=google&utm_medium=cpc&utm_campaign=shopping_us_c-craft_supplies_and_tools-raw_materials-metal-solder&utm_custom1=f643b836-1c71-435e-bd57-8fd066a8c630&utm_content=go_1843970770_72423967671_346364363889_pla-297065911891_c__130198824&gclid=EAIaIQobChMI64mR4e_95AIVo__jBx3TWwDcEAQYBiABEgLjmvD_BwE

They are faux stained glass panels, kinda like the old beer lights that hung over pool tables. They are a fiberglass. You can spray them with a cleaner like Krud Kutter. Lay a towel to catch drips. Spray... soak...spray... soak, till its all softened. you can use a soft brush (like a toothbrush) carefully. I would use mostly a microfiber cloth. Use a light hand.

GP66 should be safe and will remove build up.