Yes, I am experiencing the same issue sometimes it gives me not just Error 504 but sometimes it's 502 and 524. I don't know what's the deal right now but I guess it's on the Cloudflare system again.

As I am writing to post this reply I encounter again the error 504.

While I'm getting error 502. Seems DDoS? or just theymos doing some upgrade or what.

Not sure what is going on, but accessing bitcointalk is becoming difficult, the download time is long, the response is slow  Even when I access my messages, it is disconnected completely. This is not good at all  And this topic took a long time for me to read the content 

It's now more than an hour. I am really having very hard times browsing the forum for the last hours and so more. I think theymos is doing something in the background, otherwise, it never stays such a long time.

It's intermittent.  I found that even when I hit "Post" to reply to a topic just now and it returned 504, the post still seemed to make it through somehow.

I try with Chrome, Firefox and Brave and the situation is identical with every browser. What I can confirm is that the situation is almost identical in the past three and a half hours, it works for a moment, but still very slowly.

I check Cloudflare System Status, and today is reported only one incident (Audit Log Record Retrieval Delays) which is marked as resolved.

There are only two possible reasons for this problem, someone is nasty angry because of the price of BTC and he started DDoS attacks, or some technical hosting issues have occurred. Anyway, I hope the admin didn't take the day off, we need a fix.

I have also faced some loading problem with chrome and brave browser in my mobile. But did not try yet to browse in laptop. At first I was thinking it’s my network problem but Now seeing all are facing this. Is it another DDOS attack? Or anything else?  

Edit:

It is like that for hours. Someone is DDOS'ing. Seems to be fine right now though. I just had a bot-check recently which eliminated the all bots probably.

I wonder how much CloudFlare takes for such a "wonderful" protection

Most likely it was triggered due to BTC passing 10,000 usd.

Some fool decided to attack the forum hoping to trigger coin sales.

It is 10:25 am eastern standard time and we seem to be all good at this moment.