can you consider to replace wpa_supplicant with iwd.
Advantage of using iwd instead of wpa_supplicant is, that the ping times seem to be much more consistent and the connection seems to be more reliable.
connman fails after starting iwd.service with this error:
# connmanctl scan wifi Error /net/connman/technology/wifi: Not supported
So I guess connman should be replaced with latest version from Debian repo.