Cloudflare have announced a new storage service named R2. I get the feeling they were planning on releasing May 4th, but something slowed them down 
It uses the S3 API so is presumably compatible with Kopia. Worth a look, as pricing is reasonable, and Cloudflare have a history of offering high-performing products.
I’ll be testing their free tier and will post results in this thread.
It looks like the S3 API is not fully implemented by R2.
error: can't connect to storage: unable to determine if bucket "test" exists: GetBucketLocation not implemented
Checking their API status page suggests that this is a known shortcoming.
So it looks like we may need to wait this one out.
I’m getting following fatal error when creating snapshot in R
Snapshotting root@ubuntu-2gb-ash:/home/akash/Akash ...
- 0 hashing, 1404 hashed (21 MB), 0 cached (0 B), uploaded 21 MB, estimated 58.5 MB (35.9%) 1m19s left
! Error when processing "public/wp-includes/blocks/post-title/block.json": The XML you provided was not well formed or did not validate against our published schema.
So, it looks like Cloudflare R2 works with Kopia now through the S3 repository.
I believe the issue was that previously Cloudflare only implemented ListObjectsV2 and that was causing issues. They now support ListObjects. I just tested it myself and it seems to be working just fine.
So, it looks like Cloudflare R2 works with Kopia now through the S3 repository.
Ah! Great news. Thanks for letting us know.