Sue Marek at Ookla, the company behind speedtest.net, among other things:
AT&T and Verizon Speedtest users experienced better median download speeds on the iPhone 16e than iPhone 16. However, the opposite was true for T-Mobile users.
Verizon Speedtest users with the iPhone 16e and the iPhone 16 experienced median download speeds that lagged behind that of both AT&T and T-Mobile.
iPhone 16e Speedtest users on Verizon’s network and AT&T’s network saw higher upload speed performance than those using the iPhone 16. However, T-Mobile users experienced the opposite and had slightly higher upload speeds on the iPhone 16 compared to the iPhone 16e.
Overall, this seems like mostly good news for Apple’s modem business. The article gives additional details about why the C1 may struggle when on T-Mobile, and includes lots of charts. Everyone likes charts.