My dad has it. He got it after he reached around 60. Not sure of the cause but he used to suffer a lot in past but now he's a bit habitual to it but sometimes the ringing is higher than other times.
There's no cure for it. None of the medicine or surgery works. But what benefited him was sound therapy. He's a US government article about it.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7493236/He prefers two types of sound therapy, in one, he generates a vibrating sound as he exhales his breath.
On another, he uses some vibrating objects like singing bowl or a tuning fork.
Explore into it and find what suits you. There are different frequencies and you can try what suits you.