EAP615-Wall txpower on 5GHz limited to 21dBm

Upon configuring OpenWrt 22.03.0-rc3 in EAP615-Wall I notice that max txpower on 5GHz is limited to 21dBm while 23dBm should in theory be possible (in stock firmware I could set 23dBm, see also the datasheet )

root@ap1:~# iw reg get
global
country NL: DFS-ETSI
        (2400 - 2483 @ 40), (N/A, 20), (N/A)
        (5150 - 5250 @ 80), (N/A, 23), (N/A), NO-OUTDOOR, AUTO-BW
        (5250 - 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW
        (5470 - 5725 @ 160), (N/A, 26), (0 ms), DFS
        (5725 - 5875 @ 80), (N/A, 13), (N/A)
        (5945 - 6425 @ 160), (N/A, 23), (N/A), NO-OUTDOOR, AUTO-BW
        (57000 - 66000 @ 2160), (N/A, 40), (N/A)
root@ap1:/# iwinfo wlan1 txpowerlist
   0 dBm (   1 mW)
   1 dBm (   1 mW)
   2 dBm (   1 mW)
   3 dBm (   1 mW)
   4 dBm (   2 mW)
   5 dBm (   3 mW)
   6 dBm (   3 mW)
   7 dBm (   5 mW)
   8 dBm (   6 mW)
   9 dBm (   7 mW)
  10 dBm (  10 mW)
  11 dBm (  12 mW)
  12 dBm (  15 mW)
  13 dBm (  19 mW)
  14 dBm (  25 mW)
  15 dBm (  31 mW)
  16 dBm (  39 mW)
  17 dBm (  50 mW)
  18 dBm (  63 mW)
  19 dBm (  79 mW)
  20 dBm ( 100 mW)
* 21 dBm ( 125 mW)
root@ap1:/# iwinfo wlan1 info
wlan1     ESSID: "xxxxx"
          Access Point: xxxxxxxxxxxxx
          Mode: Master  Channel: 36 (5.180 GHz)
          Center Channel 1: 38 2: unknown
          Tx-Power: 21 dBm  Link Quality: unknown/70
          Signal: unknown  Noise: -92 dBm
          Bit Rate: unknown
          Encryption: mixed WPA2/WPA3 PSK/SAE (CCMP)
          Type: nl80211  HW Mode(s): 802.11nacax
          Hardware: 14C3:7915 14C3:7915 [MediaTek MT7915E]
          TX power offset: none
          Frequency offset: none
          Supports VAPs: yes  PHY name: phy1

Since I have two EAP615 devices I compared the one with stock- and OpenWrt 22.03.0-rc3 firmware with https://vremsoftwaredevelopment.github.io/WiFiAnalyzer/ and signal strength is comparable so I am wondering if this is perhaps only a display issue?