I always use Tor for reddit.com, amongst other websites, and occasionally would get a 503 Service Unavailable response. Hitting F5 or new circuit for this site usually clears this. Now 503 Service Unavailable solidly for the last few days.
On Windows 10 desktop with ExpressVPN. I have tried both Tor browser and Brave Browser private window with Tor with the same outcome. I have also tried disconnecting ExpressVPN. I've deleted Tor and downloaded it again. No luck. All other sites I've accessed load OK without the 503 message. Does reddit now blocking Tor or do I have a browser configuration issue?