pfSense

When a wifi interface is configured the wlan interface is created at boot and then renamed appropriately.
However in 22.01 that process is run twice resulting in an additional wlan interface:

Mar 30 01:08:17     php     499     rc.bootup: Cloning new wireless interface ath0_wlan0
Mar 30 01:08:17     kernel         wlan0: Ethernet address: 04:f0:21:0f:7f:7f
Mar 30 01:08:17     php     499     rc.bootup: Cloning new wireless interface ath0_wlan0
Mar 30 01:08:17     kernel         wlan0: changing name to 'ath0_wlan0'
Mar 30 01:08:17     kernel         wlan1: Ethernet address: 06:f0:21:0f:7f:7f 

wlan1 remains when bootup is complete.

ath0_wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        description: WIFI
        ether 04:f0:21:0f:7f:7f
        inet6 fe80::6f0:21ff:fe0f:7f7f%ath0_wlan0 prefixlen 64 scopeid 0xc
        inet 192.168.58.1 netmask 0xffffffc0 broadcast 192.168.58.63
        groups: wlan
        ssid Test2 channel 3 (2422 MHz 11g ht/40+) bssid 04:f0:21:0f:7f:7f
        regdomain ETSI country GB indoor ecm authmode WPA2/802.11i
        privacy MIXED deftxkey 3 AES-CCM 2:128-bit AES-CCM 3:128-bit
        txpower 30 scanvalid 60 protmode OFF ampdulimit 64k ampdudensity 8
        shortgi -ldpc -uapsd wme burst -apbridge dtimperiod 1 -dfs
        parent interface: ath0
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11ng <hostap>
        status: running
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
wlan1: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 06:f0:21:0f:7f:7f
        groups: wlan
        ssid "" channel 3 (2422 MHz 11g ht/40+)
        regdomain ETSI country GB indoor ecm authmode OPEN privacy OFF
        txpower 30 scanvalid 60 protmode CTS ampdulimit 64k ampdudensity 8
        shortgi -ldpc -uapsd wme burst dtimperiod 1 -dfs bintval 0
        parent interface: ath0
        media: IEEE 802.11 Wireless Ethernet autoselect <hostap> (autoselect <hostap>)
        status: no carrier
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

If you have multiple VAPs configured this happens to each one resulting in numerous additional wlan interfaces:

Mar 29 23:50:59     kernel         wlan: mac acl policy registered
Mar 29 23:50:59     php     499     rc.bootup: Cloning new wireless interface ath0_wlan0
Mar 29 23:50:59     php     499     rc.bootup: Cloning new wireless interface ath0_wlan1
Mar 29 23:50:59     kernel         wlan0: Ethernet address: 04:f0:21:0f:7f:7f
Mar 29 23:50:59     kernel         wlan0: changing name to 'ath0_wlan0'
Mar 29 23:50:59     php     499     rc.bootup: Cloning new wireless interface ath0_wlan0
Mar 29 23:50:59     kernel         wlan1: Ethernet address: 06:f0:21:0f:7f:7f
Mar 29 23:50:59     kernel         wlan1: changing name to 'ath0_wlan1'
Mar 29 23:50:59     kernel         wlan2: Ethernet address: 0e:f0:21:0f:7f:7f
Mar 29 23:50:59     php     499     rc.bootup: Cloning new wireless interface ath0_wlan1
Mar 29 23:50:59     kernel         wlan3: Ethernet address: 0e:f0:21:0f:7f:7f

Tested:

22.01-RELEASE (arm64)
built on Mon Feb 07 16:39:19 UTC 2022
FreeBSD 12.3-STABLE