I use github and gmail auth all the time on other sites, so it's probably not that. In fact, I did use github in this case and that worked fine.
I think it was when I was first entering the problem statement which eventually becomes the title of the post, but starts out as a search.
As for the public vs private help form,
The help link goes to a page with distinct links that appear different, where one says clearly "ask the community" and another says "To send a bug report or a feature suggestion, ...". I claim that it is not my failure to get this wrong.
There is also yet another seperate link that says email support, so, I suppose I should have used that, except I didn't specifically need the support request to be private or one-on-one, I just mean to say that the page and wording did not convey to me that I was about to post to a public discord, especially when there was another link nearby but seperate that DID clearly advertise that. I thought I was filling in a typical customer support form. Only after submitting and the post is displayed did it look like a post on a public forum.
All in all, I think I want to complain about the unclarity and behavior of this other stuff as it's own problem besides the login token problem. I would have said the login problem was probably my security/cookie settings in firefox, except I had no such problem for over a month already in the same browser with the same settings, and only just the last few days have the problem since switching to the family plan.
Which was also yet another annoyance, I could not simply upgrade my existing plan, I had to make a new one and delete the old one, and on top of that, the duo plan was singularly excluded from the pay yearly option.
Each of these things (besides the actual login token thing) is little, but consider the whole experience for a second. I keep getting hit with this invalid login thing after i've already logged in and used the service for a while. When the search box in my browser doesn't "just work", google or ddg with all their problems are better than getting this login thing at random points while I'm trying to do whatever else I'm trying to do be it work or play. Then when I click "help" to resolve that issue, and what follows from that is this sequence of rough edges and annoyances, remember the only reason anyone ever would click on "help" is when they have already had to suffer some problem, it's no longer the time to to have rough edges and ask them for understanding. Altogether it makes you go wait a minute... and I'm paying $15/month for this? When everyone else in the world would say is crazy to pay one cent for a search engine for the obvious reason. Yeah I'm paying for a reason so no need to tell me what I'm paying for. Just, this other stuff is also true.
And on top of that, I'm probably not even talking to anyone from Kagi right now, and will probably just get annoyed responses from other users who see this as just a bunch of whining, after I clicked on the help link from the main kagi page.