A new version was released today/yesterday in F-Droid. I've just upgraded and the first thing it says is "What's new in 4.3.5. New, faster Version 2 (OpenGL) map rendering engine, with 2.5D view"

Edit: Also, thanks to the replies here, I see that 4.3.5 was actually released in F-Droid on the 1st January, and 4.3.8 is also available since yesterday so I upgraded twice today already.

F-Droid does not always install the very latest versions by default unless you turn on Settings > Expert mode and then tick Unstable updates.

Nope, version 4.3.5 was posted to F-Droid right around the New Year.

https://f-droid.org/en/packages/net.osmand.plus/

"Suggested" version on F-Droid is an older one, but you can choose to update to a newer one way at the bottom under Versions.

Edit: I updated my repositories (pull down on main screen) and now 4.3.5 is the Suggested version.

Update your repos. The current version on fdroid is 4.3.8, released yesterday.

I got the update an hour ago, try refreshing repositories.