Le Wifi tombe en mode Clamshell

J'ai un MacBook Pro (13 pouces, M1, 2020) en mode clapet, connecté à un moniteur 4k et alimenté par un hub USB-C. Si je n'utilise que l'écran externe, avec le couvercle fermé, le wifi devient inutilisable. Dès que j'ouvre le couvercle (les deux écrans allumés, en miroir), le problème disparaît.

En mode fermé :

moe@Moes-MBP ~> ping google.com
PING google.com (142.250.217.110): 56 data bytes
Request timeout for icmp_seq 0
64 bytes from 142.250.217.110: icmp_seq=1 ttl=117 time=254.020 ms
64 bytes from 142.250.217.110: icmp_seq=2 ttl=117 time=206.079 ms
Request timeout for icmp_seq 3
64 bytes from 142.250.217.110: icmp_seq=3 ttl=117 time=1207.436 ms
64 bytes from 142.250.217.110: icmp_seq=4 ttl=117 time=214.452 ms
64 bytes from 142.250.217.110: icmp_seq=5 ttl=117 time=224.992 ms
64 bytes from 142.250.217.110: icmp_seq=6 ttl=117 time=230.388 ms
^C
--- google.com ping statistics ---
8 packets transmitted, 6 packets received, 25.0% packet loss
round-trip min/avg/max/stddev = 206.079/389.561/1207.436/366.069 ms

Immédiatement après l'ouverture du couvercle :

moe@Moes-MBP ~> ping google.com
PING google.com (142.250.217.110): 56 data bytes
64 bytes from 142.250.217.110: icmp_seq=0 ttl=117 time=17.263 ms
64 bytes from 142.250.217.110: icmp_seq=1 ttl=117 time=17.297 ms
64 bytes from 142.250.217.110: icmp_seq=2 ttl=117 time=44.884 ms
64 bytes from 142.250.217.110: icmp_seq=3 ttl=117 time=13.996 ms
64 bytes from 142.250.217.110: icmp_seq=4 ttl=117 time=19.013 ms
64 bytes from 142.250.217.110: icmp_seq=5 ttl=117 time=22.815 ms
^C
--- google.com ping statistics ---
6 packets transmitted, 6 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 13.996/22.545/44.884/10.329 ms

Quelle en est la cause ?