Oneliner that you can paste in the browser's console to find and dump/download all currently loaded Canvas elements

dumpCanvases.js

document.querySelectorAll('canvas').forEach((c,i)=>{try{const d=c.toDataURL();console.log(`Canvas ${i+1}: ${c.id||'no-id'} (${c.width}x${c.height})`,d);const a=document.createElement('a');a.download=`canvas_${i+1}_${c.id||'unnamed'}.png`;a.href=d;a.click();}catch(e){console.log(`Canvas ${i+1} error:`,e.message);}});