I'm guessing this is a joke?

Why would saying that Postgres is a mature database - more mature than SQLite - be a joke?

SQLite is probably more mature than Postgres in terms of service hours.

I understood the comparison to be with Litestream, not SQLite in general.

Why would we compare Litestream (a backup solution) with Postgres (a database)? Would be like comparing Linux with NGINX.

Postgres has a similar replication solution built-in. It's like comparing Samba with Windows Server if your purpose is to run a SMB file server.

Both are mature. There are way more sqlite databases running than postgres. The code base is smaller and has less new features added to it every year. What is unstable with sqlite?