JG:
Unknown, likely unknowable. Other than some anecdotal online posts last year claiming 12-16 weeks. Obviously can't vouch for the validity of those posts.
I do know that Namibia requires:
1 - A MIMIMUM of 6 months of validity from the date of your scheduled DEPARTURE from Namibia
2 - A MINIMUM of 6 blank visa pages when you enter Namibia. A "blank page" is defined as a single side of each physical page/sheet. You have to remember, if you clear immigration at any point along the way while in transit, you will receive a "stamp" of some sort in your passport. So, if you leave the secure area in say Frankfurt or Amsterdam, Zurich etc or in this case Jberg to overnight at City Lodge, your passport will be stamped twice - once entering the country and once on departure. Depending on the size of the stamp, they could be on the same single page or take up a full page for each. Your passport will also be stamped in Jberg just going thru the transit corridor to catch a connecting flight.
In my current one, I have some that are physical sheets that are pasted in that take up an entire page. Other pages have up to six different stamps on the page.
Bottom line to me is, if it expires anytime this year (2022), and you even remotely think you might need it, I'd get it submitted ASAP.
