hostapd_config.py in autotests has the below code snippet (see [1]). 
Tracking the git history of this snippet is a bit tricky as the file was moved around. 
I do not understand why we would want to report 11A or 11G when we are really on 11N or 11AC. The returning 11G by default somewhat makes sense given that traditionally hostapd_config inits with a default 11 G config (a CL to change that is at [2]). 

Why is this problematic? It confuses wifi developers and whoever else these test results are sent to (e.g. rf engineers). I sent the results in [3] to someone and they came back with a response that included "Another finding is that the test mode is listed as "mode11a", which seems to be a legacy rate with only 20 MHz support." 


[1] 
if self._is_11n or self.is_11ac:
  # For their own historical reasons, hostapd wants it this way.
  if self._frequency > 5000:
    return self.MODE_11A
  return self.MODE_11G
  raise error.TestFail('Invalid mode.')

[2] https://chromium-review.googlesource.com/#/c/chromiumos/third_party/autotest/+/720102/

[3]
[##] Results from the latest build on Eve 

ch044_mode11A_none_PSon_signal{perf}=-22

ch044_mode11A_none_PSon_tcp_tx_throughput{perf}=168.21+-1.35
ch044_mode11A_none_PSon_tcp_rx_throughput{perf}=248.53+-40.12

ch044_mode11A_none_PSon_udp_tx_errors{perf}=0.00+-0.00
ch044_mode11A_none_PSon_udp_tx_throughput{perf}=210.39+-1.14

ch044_mode11A_none_PSon_udp_rx_errors{perf}=0.00+-0.00
ch044_mode11A_none_PSon_udp_rx_throughput{perf}=230.06+-1.67

ch044_mode11A_none_PSoff_signal{perf}=-22

ch044_mode11A_none_PSoff_tcp_tx_throughput{perf}=180.28+-0.78
ch044_mode11A_none_PSoff_tcp_rx_throughput{perf}=271.33+-32.77

ch044_mode11A_none_PSoff_udp_tx_errors{perf}=0.00+-0.00
ch044_mode11A_none_PSoff_udp_tx_throughput{perf}=210.52+-1.30

ch044_mode11A_none_PSoff_udp_rx_errors{perf}=0.00+-0.00
ch044_mode11A_none_PSoff_udp_rx_throughput{perf}=329.95+-1.61

ch157_mode11A_none_PSon_signal{perf}=-24

ch157_mode11A_none_PSon_tcp_tx_throughput{perf}=168.23+-0.23
ch157_mode11A_none_PSon_tcp_rx_throughput{perf}=256.94+-24.61

ch157_mode11A_none_PSon_udp_tx_errors{perf}=0.00+-0.00
ch157_mode11A_none_PSon_udp_tx_throughput{perf}=210.24+-1.28

ch157_mode11A_none_PSon_udp_rx_errors{perf}=0.00+-0.00
ch157_mode11A_none_PSon_udp_rx_throughput{perf}=225.44+-0.70

ch157_mode11A_none_PSoff_signal{perf}=-24

ch157_mode11A_none_PSoff_tcp_tx_throughput{perf}=179.05+-1.33
ch157_mode11A_none_PSoff_tcp_rx_throughput{perf}=258.94+-30.15

ch157_mode11A_none_PSoff_udp_tx_errors{perf}=0.00+-0.00
ch157_mode11A_none_PSoff_udp_tx_throughput{perf}=209.67+-2.33

ch157_mode11A_none_PSoff_udp_rx_errors{perf}=0.00+-0.00
ch157_mode11A_none_PSoff_udp_rx_throughput{perf}=323.56+-0.85