The ETSI limitation of 14dB ERP is referred to a half-wave antenna (which has a gain of 2.15dB compared to an isotropic antenna). Therefor, a Max EIRP of 16.15 dB (EIRP = ERP + 2.15dB) is allowed for EU (to get the same field strength when using an isotropic antenna).
As our module is designed to have an isotropic radiation pattern and the maximum power of the SX1261 is 15 dBm, the Max EIRP (in liaison with the LoRaWAN Regional Parameters v1.0.2) is defined as follows:
TXpower 0: 15 dBm
TXpower 1: 14 dBm
TXpower 2: 12 dBm
TXpower 3: 10 dBm
TXpower 4: 8 dBm
TXpower 5: 6 dBm
TXpower 6: 4 dBm
TXpower 7: 2 dBm