Do you have any good advice for me?

Actually, I do) I had the same problem today. Try to log in from another browser. Opera worked for me, for example.
Thanks! I just tried to login via Brave Browser instead of Firefox and have come one step further to insert my mail. But waiting for the code last forever again like yesterday....
Have had no login problems for so many days but whats wrong now?
You may have a temporary network issue, so you can try again later or clear your data and try logging in again. I also used the Brave browser and logged in there, and it worked without any issues. You can try again, and maybe the issue is resolved now. Still, if the problem is not resolved, then there is a @Whale here. He will definitely talk to their team about it and if there is any technical problem, they will solve it.
Well, going through the thread, I see that alot of users were having issues with the site working well on one browser and not working well on another, this i would say is a more likely an issue from the backend Code of the website, the team still need to get to work to ensure they site works well on all browsers without any form of issues.
I remember some weeks back when I tried accessing the site from my Samsung browser, the site did load properly and opened normally but I was unable to log in as my login option, which is telegram wasn't working no matter how much or how many times I tried, I later the same day decided to try accessing the site again but this time, I made use of my chrome browser, and amazingly, easily logged in without any form of issues through the same telegram login option.
So, the whale casino team will need to work hard to ensure that the site is working well across all Browsers.