Apps Script web suddenly not working for users

Question

A few days ago I made a simple form in apps script for some users (max 20 people, I'd say) in our company to insert some data and to keep track of it in a spreadsheet for later usage. Until yesterday it worked with no problems at all, but today morning it simply shut down for everyone except for me or any new user I add (I made some testing with other Google Accounts that I own and I can access to the form no problem with them and also in different devices!), but I've been told that this is what everyone is seeing when they try to open it:

SCREENSHOT ERROR

The narrowing that I made so far:

• We don't use company-emails, so it can't be that.
• The implementation access is set to any user (just like in the beginning).
• I made sure several times they all have access to the spreadsheet.
• They also cannot make it work in Incognito mode.
• I tried to re-do absolutely everything: The spreadsheet, the form (hence, the implementation), changing and rechangin access permissions and all...but still nothing
• Also made sure they didn't have multiple Google Accounts logged in the browser that could potentially create some conflict.
• Last time I changed the code was yesterday around 11am (a simple logic error that I was having), and last connection (not from me) was 2pm. So I really don't think is a code problem.

I have no clue where to go from here, so any new ideas are totally welcome. If there's any more information that I can provide to enlight the situation some more, please let me know!