Just recently went to check integrations that indicated that were having issues and were disconnected and noticed that Battle.net was one of them. Tried to connect and it let me login and verify my account then it just hangs infinitely without connecting.

This might be a me issue or something that is occurring to others or something that has occurred recently. Hopefully its something which is fixed or someone has a solution to.

I'm having the same issue. I can get as far as entering login details and verifying with the authenticator, but it never completes the process.

It connects for me, can you provide a debug log?
You can find it in C:\ProgramData\GOG.com\Galaxy\logs

That's so weird. I deleted the log so I could get a new clean log file, and it worked. Previously, it would leave a blank login screen that wouldn't close after authentication. Now it closes.

2023-06-27 01:24:32,700 - root - DEBUG - Request to [url=https://eu.account.blizzard.com:443/oauth2/authorization/account-settings]https://eu.account.blizzard.com:443/oauth2/authorization/account-settings[/url] responsed with status code 200
2023-06-27 01:24:33,511 - root - DEBUG - Request to https://eu.account.blizzard.com/api/games-and-subs responsed with status code 500
2023-06-27 01:24:33,511 - root - DEBUG - Sending data: {"jsonrpc": "2.0", "id": "37", "error": {"code": 4, "message": "Backend error"}}

battle.net connection in GOG Galaxy shows "403 forbidden" since yesterday.

I've been having the same problem (Lost Connection) for several months. I get it working for a day or so and then it shows disconnected. When it is connected, not all of my games are showing up.

Same issue here

it started later for me, but yeah, i'm having the same problem.

It hasn't worked for me since late last year. I would try every few weeks, but always get the '403 Forbidden' error.

Mine stopped working about the same time my Battle.net integration also stopped working, late last year. I will try to log in to my Steam Account, I will get the Steam Guard Email authentication, enter the code and... nothing. It just tells me that Steam is Offline.