WPA3 Transition Mode can be a temporary solution on the WPA2 to WPA3 evolution.
However, there are concerns that some old devices won’t be able to connect to a WPA3-TM SSID anymore, and if WPA2 security is broken, your WPA3 is also compromised, since they share the same passphrase.
The goal is really to have a massive switch to WPA3 only networks, which is the only method supported on 6 GHz btw.
This is how WPA3-TM looks like on a beacon frame.
If you look for the RSN Information in the tagged parameters, you can see that 2 AKMs are being used: one PSK (2) and one SAE (8), which are WPA2 and WPA3 respectively.
It is expected that devices supporting WPA3 will select the AKM = 8, while older devices will select AKM = 2.
However, this does not seem to be always true, and some of them will simply refuse to connect to the SSID.
I am still testing my device to check if they will behave properly connecting to this SSID.
Newer ones could connect with no problem, selecting WPA3, as expected.
Have you experienced any issues using WPA3-TM?