I had a similar concern with even new cages. New iron bar cages are still painted, and can still chip and flake over time and use. Back when I was getting a TAG, I spoke to the avian vet. She said it is a concern, but paints today used for cages are safer since they don't have toxic resins that can be absorbed. It's more like plastic that will just pass thru their system if a piece flakes off.
As for what I did when I took home my baby TAG at just a few months of age, I kept her in a typical CalCage for months and looked for what I thought would be the best cage for her many years that lay ahead. I ended up with a much higher quality and larger cage made of natural materials that don't need paint. A 4-foot wide x 3-foot deep aluminum frame cage that is 7-foot tall, stainless steel wire, glass doors, mananita branches, and sisal climbing ropes. Other than toys, all natural. And she has full spectrum 12-hour timed lighting, a HEPA air purifyier, and since she loves TV, her own flatscreen TV up against a glass panel. Perhaps overkill, it's more like a zoo habitat, but she means so much to me. Her cage door is always open when I am home. Sure she is excited when I get home to come out and fly, get a good frisking of feathers and play and such. However, she adores her cage. And often spends hours in there on weekends when I'm home all day.