As per my knowledge - 2x2:2 Access points can be powered on with PoE (802.3af) capable switch port. anything beyond these specs e.g. 4x4:4 (MR44 5GHz) require PoE+ (802.3at) power to function in full power mode - with all four transmit, receive antenna and spatial streams functioning as per specification.
MR44 can be powered on with PoE (802.3af) switch port but then its 5GHz specifications will be reduced to 2x2:2 instead of 4x4:4.
below is the extract from Datasheet of MR44
- Power over Ethernet: 42.5 - 57 V (802.3at) or 37 - 57 V (802.3af) - low power mode ***
- Power consumption: 30W max (802.3at) or 18W max (802.3af) - low power mode ***
MR44 | Cisco Meraki
hope this answers your question.