Will the color of tea leaves change when soaked in travel cups?

Will the color of tea leaves change when soaked in travel cups?
There are various types of tea sets, but from a scientific perspective, metal tea sets, enamel tea sets, plastic tea sets, and insulated cups are generally not ideal for brewing tea. Metal tea sets with high content of gold, silver, lead, and copper, due to wear and tear, can increase the absorption of these metal components by the human body through brewing tea, which is detrimental to human health.
Enamel tea sets, although having advantages such as being less prone to cracking and durable, have poor tea brewing effects, especially when the enamel breaks and exposes the iron skin, which will further affect the quality of tea brewing, causing the tea to lose its original flavor, turn yellow in color, and have a cooked soup flavor.
After brewing tea in plastic cups with boiling water, there are often some unpleasant or harmful substances that dissolve, which not only affects the taste of the tea but also is not conducive to human health.