I'm trying to set responsive values for columns in footer:

but it returns error:undefined when I hit "Apply". and values are never saved:

Seems like your ajax doesn't play well with https:

Helix ultimate 2.0.11, J4, php8.0.8
How to fix this bug?
UPDATE:
Actually it doesn't "apply" ANYTHING. I'm getting this same error whatever I'm trying to do.
I've already turned off "force https" in general/server settings and even disabled http-headers plugin from Joomla, so the only thing left is http->https redirection on my prod server, which I'm not able to turn off and actually I'm NOT GOING to, because it's lame to use http these days, when google bans you if you're not https.
Everything worked fine on J3+php7.4
WTF, guys?