Weebly won't load when cross-site cookies blocked

[mikedotexe]

Description

When logging into a Weebly website (one of those point-and-click content management platforms) editor, the page won't load and instead show an eternal spinner until you select "All cookies allowed" from the Brave options.

Steps to Reproduce

1. Log into a Weebly account
2. Click "Edit Site"
3. See infinite spinner

Actual result (as well as solution):

Expected result:

The page's spinner will stop at some point and load the page.

Reproduces how often:

Every time.

Brave version (brave://version info)

Brave	1.0.1 Chromium: 78.0.3904.108 (Official Build) (64-bit)
Revision	4b26898a39ee037623a72fcfb77279fce0e7d648-refs/branch-heads/3904@{#889}
OS	macOS Version 10.14.6 (Build 18G84)
JavaScript	V8 7.8.279.23
Flash	(Disabled)
User Agent	Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36
Command Line	/Applications/Brave Browser.app/Contents/MacOS/Brave Browser --enable-dom-distiller --disable-domain-reliability --no-pings --extension-content-verification=enforce_strict --extensions-install-verification=enforce --enable-oop-rasterization=Enabled --sync-url=https://no-thanks.invalid --enable-features=SimplifyHttpsIndicator,NewExtensionUpdaterService,PasswordImport,WebUIDarkMode --disable-features=AutofillServerCommunication,LookalikeUrlNavigationSuggestionsUI,NotificationTriggers,AudioServiceOutOfProcess,SmsReceiver,SyncUSSBookmarks,UnifiedConsent --flag-switches-begin --flag-switches-end
Executable Path	/Applications/Brave Browser.app/Contents/MacOS/Brave Browser
Profile Path	/Users/mike/Library/Application Support/BraveSoftware/Brave-Browser/Default

Miscellaneous Information:

I see there's a Github issue label workaround/allow-all-cookies which could be added to this issue.
I wonder if there's a feature request in here somewhere that would have a teeny popup that suggests to end users, "this website might need all cookies enabled" or something. We certainly can't compile a list for every website, but might possibly compile a list of major sites where this applies.

[mikedotexe]

I'll make this a "thread" of sorts pointing out sites that need to allow All Cookies. I think it'd be great to have a feature that non-obtrusively suggests to users that the website they're visiting may need altered settings.
ETHDenver for 2020 is set up on a website called Devfolio. The sign-in doesn't work unless you allow All Cookies.
https://devfolio.co/signin

[AoDev]

I have this issue in a different context: in development.
I have an API server running locally at localhost:3001 while my frontend is at localhost:3000.

I had no problem with this until today. (Maybe Brave update?)

While I can unblock this easily on my local machine, it took me a while to find out why things broke suddenly.

Since I am no expert, I am wondering what happens in production. So far it seems to still work properly having our api at api.mydomain.com and frontend at mydomain.com.

I thought subdomains cookies would also be considered cross-site because the Set-Cookie header needs to declare the domain for subdomains to share cookies. Am I wrong? I'd rather avoid a bad surprise where our site suddenly stops working for our Brave users.

[rebron]

cc: @ryanbr

[rebron]

@mikedotexe Thanks for the report. Leet's keep this one specific to Weebly. The workaround/allow-allow-cookies (and there are other webcompat tags for specific issues) will list out the websites instead of having all websites listed in one issue. Would be great if you could file a separate one for: https://devfolio.co/signin

[ryanbr]

The main issue here, weebly is calling cookies from editmysite.com, which is why its weebly having issues. Currently we don't have a whitelist to allow all cookies just yet, so just allow all cookies for the time being.