Basecamp 4.8.13 for Mac is available.

Change log says "Fixed compatibility issues with some devices"

And:
"Changes made from version 4.8.11 to 4.8.12:
Fixed map rendering issues
Stability improvements and bug fixes"

Ver 4.8.13 appears to pave the way to upgrading my iMac to macOS Ventura and continuing to use Basecamp without the need to use it in the inferior 3D display. If so, hooray! 

Whatever happened to Garmin's adamant statements indicating 'no further development of Basecamp Mac' ?? If vocal pressure from this and other forums made the difference, thank you all!

This isn't development. No change in functionality but Garmin always said they would update it if needed to correct certain compatibility issues.

Sadly hasn't improved the 2D view on my Mac running Ventura, still having to use 3D

So, Skellum, you still get the repeating beachball spin in 2D?

Anybody know, what were the compatibility issues and map rendering issues that they 'fixed'? and what stability improvements? If it wasn't to allow productive use in 2D under Ventura, then why bother?

Previously I was using 4.8.11 and did not have the Beachball spin, just the very slow and unmanageable map rendering whilst using 2D - having now updated to 4.8.13 it appears to be exactly the same so back to 3D again!

For the record:

I upgraded my Intel Core i3 iMac (2019) to macOS Ventura 13.4.1 and running BaseCamp v4.8.13 works perfectly well. Oh, it still has all of its usual inherent quirks that I've gotten used to, but it runs just as smoothly as ever, anyway. And, 2D view works fine.

Next step will be to see how it fares with an M1 chip iMac, if I ever make the upgrade.