In this part of World we are taking green tea mixed with salt (Nacl) and sodium bicarbonate. In Kashmiri language we call it "Mamkeen Chai"( Salty tea). Many Reserachers from this part of word believe that Mamkeen tea is responsible for High incidence of Gastric malignancies in Kashmir.
I used to find that patients thought that green tea was healthy; however, if they had overactive bladders, the caffeine in green tea used to aggravate their bladder symptoms, so I used to advise a slow transition (to avoid headaches) onto decaf drinks.
This paper gives the caffeine content of teas:
Chin, J. M., Merves, M. L., Goldberger, B. A., Sampson-Cone, A., & Cone, E. J. (2008). Caffeine content of brewed teas. Journal of analytical toxicology, 32(8), 702-704.
https://www.researchgate.net/publication/23471909
. . and this relates to why this is:
Lohsiriwat, S., Hirunsai, M., & Chaiyaprasithi, B. (2011). Effect of caffeine on bladder function in patients with overactive bladder symptoms. Urology annals, 3(1), 14. Urology annals, 3(1), 14.
https://www.researchgate.net/publication/49967512
However, the authors attribute this to the diuretic effect, which does not answer your question relating to the bladder mucosa.
It is a well known fact that the salty chai or green tea is taken almost every morning,this is known build up the body salt and cafaine level. This raises the blood pressure which is not healthy. Hot infusion in water without salt is recommended.