Change S3 Storage Classe

I have a server in production and I would like to know if there is any risk when changing the S3 Storage Class from Standard to Standard Infrequent Access.

I would also like to know if this is a real way to reduce storage costs and if there is another way to reduce the cost, such as cleaning old files.

It could be slower. Also I think there is a minimum charge, so it could make some objects that are removed fast again more expensive. I’d advise looking into enabling Intelligent tiering.

You can increase compression strength in the advanced settings, though that probably doesn’t help much.
The best option is to store less backups or to look into excluding more files from backup.