DeletedUser84 I was not familiar with Lunatask, but it looks really interesting. Thanks for sharing.
This page mentions some of their encryption and privacy properties, including encryption algorithms, server information (Amazon Web Services), and analytics (Plausible Analytics). I'm not an expert, but all of that looks pretty good.
Two major downsides.
Metadata is not encrypted. Depending on your threat model this could be a nonstarter.
Lunatask is proprietary and closed source, relies on a subscription or a one-time fee for full features, and seem to only be available on Google Play. Depending on your values, resources, and/or threat model these could also be nonstarters.
Overall, it certainly looks like it is a more private service than something like Todoist. However, it doesn't look as private as something like Standard Notes. Whether Lunatask's balance of privacy, features, and cost is worth it is up to each person.