It's hard to tell! There are a couple of different routers and several WiFi extenders, some of which may be a true Mesh and others which almost certainly are not.
What would "I" class as a true Mesh setup? Most importantly that data is selectively transmitted rather than everything being re-transmitted. Add one none-Mesh extender and your WiFi bandwidth will slow to half the speed of the slowest out of the router and the extender, add another none-Mesh extender and it'll drop by half again (and so on). In a Mesh system, data transmitted over the Mesh nodes (but not directly between the router and user devices) takes up approximately twice as much bandwidth, but it's only the targetted transmitted data not all the background (unnecessary - untargeted) data, and that overhead doesn't increase greatly depending on the number of nodes (though latency does increase).
Even better, if your Mesh nodes seamlessly hand over connected devices between themselves without you even noticing. To be fair for this to work properly both the Mesh nodes and your devices need to have been designed with this in mind (most WiFi5 Wave2 and later, even some WiFi 4 devices, will do this).
Where does it fall down? I've found you still have to prevent some devices from roaming! If my WiFi printer for some inexplicable reason roams halfway through a print, it'll stall, as will the Stadia game controllers (though not for much longer).
