Just want to chime in with info that is not fully up to date, but I would wager probably still mostly right...
Frame has been developed at LI for the past 10+ years as a "virtual feature store". It is an abstraction where features can be defined and have "anchors" in various environments. Notably, the feature data can be available offline (e.g., in an Iceberg table), nearline (e.g., in a Kafka topic) or online (e.g., in Venice, but also in other online services: Pinot, Search, even REST services, etc.). So Venice is one of many systems capable of hosting and serving "online anchors", and it happened to be the most popular choice of online anchor for online feature access.
A few years ago, some fraction of the Frame project (which corresponded mostly to the "offline anchors" part, NOT the online side) was carved out and copy-pasted into GitHub under the name of Feathr. There was originally an intent to migrate the internal frame-offline users over to Feathr (which at some point in time were pretty similar) but that effort was never funded in earnest. So at this point, LI's Frame and the open-source Feathr diverged, with most of the Feathr development being supported by a team at Microsoft. In other words, although the two projects are similar, LI never actually used Feathr.
Later, Frame was kind of put on the backburner, and efforts have been diverted to other projects (e.g., Feature Cloud, Feature Marketplace, and a bunch more code names I don't remember). These other projects may have reused some stuff from Frame, but Frame itself was kind of put in maintenance mode. I'm not exactly sure about that part, it's just what I heard. That being said... not investing further into something, while also not investing into migrating out of it, means that there is probably still a significant internal user base of legacy use cases stranded on Frame.
Unfortunately, that has become quite common at LI over the past years. LI used to be really good at orchestrating large migrations, but not so much anymore... teams and/or managers abandon projects because they don't want to invest in them, but don't invest in actually migrating out of them, so there's this wishful thinking that users will just kind of move out of their own volition, perhaps aided by the increasing friction of trying to use an unsupported system. The Venice team has historically tried hard to keep supporting whatever functionality it has users for, and to cleanly deprecate and delete stuff rather than just letting it rot, though it is a lot of work to do this right... All that to say, the above indictment of LI engineering work ethics is a general observation and should not automatically be transferred over to the Venice team and project, but it may serve to understand what is going on with some of the other LI-led projects, both internal and open-source.