It's pretty easy to get some hard data, it's an open source project. I went to https://github.com/tursodatabase/turso/pulls?q=is%3Apr+is%3A... and looked at the last few PRs:

https://github.com/tursodatabase/turso/pull/4824/files "some performance improvements", no new tests

https://github.com/tursodatabase/turso/pull/4820/ "fix wal checkpoint", one basic test

https://github.com/tursodatabase/turso/pull/4815/ "Optimizer: fix bugs, improve cost model", a lot of nontrivial logic, no new tests

https://github.com/tursodatabase/turso/pull/4814 "WAL auto truncation: increase epoch to prevent stale pages reuse", there's a new test with a comment "It is slightly fragile and can be removed if it will be unclear how to maintain it"

https://github.com/tursodatabase/turso/pull/4806/ "Busy snapshot bugfix" with two new tests with the same comments as 4814 (I guess they didn't fix the bug in one go?)

https://github.com/tursodatabase/turso/pull/4802/ "fix/translate: revert change that allowed index cursor with stale position to be read", fixes a data-corrupting bug, there's a regression test, good (although the original bug sounds like it should've been caught by a suite like the one SQLite has)

That's just a couple days worth of PRs.

This style of development does not inspire confidence. They develop features, sure. But I want my database to be rock-solid and completely covered by tests, not just move fast and break things. It's not FUD to just look at how they approach PRs.