The m4 iPad Pro does not have mmWaveTo give you some idea, an M5 iPad Pro with only 256Gb storage + cellular is also £1500 new from Apple, the same price.
So it was a calculated decision in terms of cost, the M4 2Tb has 16Gb ram verses 12Gb ram in the M5. It also has 4 P cores verses 3 P cores in the M5. Also the M4 has Qualcomm with mmWave capability.
I lose out in terms of the 30% graphics increase found in the M5, but I assume a 10 core M4 should be quicker otherwise than a 9 core M5 even taking into account a 15% increase in CPU performance. I don't know if an increased refresh rate for external displays or the improved ssd performance would have made the M5 worth it.
New iPad Pro Lacks mmWave 5G and Ultra-Wide Camera
While the iPad Pro was updated with the M4 chip and more today, the latest 11-inch and 13-inch models lack two features that are available on some previous models, including mmWave 5G support and an Ultra Wide camera. Apple's comparison page confirms that cellular configurations of the new iPad...
Also, as the owner of the m4 and m5, the C1 and N1 are incredible. The wifi and cellular reach are much better in my environment. Some testing says apples might be slightly slower but ultimately, I get stronger WiFi signal throughout my house and in areas I never did. I also get better cellular connectivity at my parents house, which was in a dead zone for my M4 and earlier iPads and iPhones.