I've been thinking lately about how e621 remains as one of the last mainstream furry webpages that permits cub content.
Over the past decade, the number of places on the internet that cub content is able to be posted has dwindled.
Fur Affinity was one of the first to ban cub, over ten years ago now, after being shut out by payment processors.
Other furry gallery sites that were founded after FA's purge banned cub content right from day one.
Even some non-furry social media have cracked down on cub, notably including Reddit and Discord.
Tumblr banned all porn, including cub, and is now deserted.
As far as large furry sites that allow cub, it has essentially come down to e621 and Inkbunny (and Twitter as far as general social media, ironically)
Inkbunny will likely never ban cub for as long as it remains solvent, due to the majority of users there being cub creators and consumers.
e621, however, seems to have more exposure to external pressure on this issue.
e6 has significant user overlap with internet spaces actively seek out 'problematic' fictional content to shun, and insist that any such fictional content must be censored.
As the anti-cub segment of the furry community grows in size and influence, it seems a reasonable question to pose of how much longer e6 can withstand the financial and reputational risk that comes with this content.
I think it's worth noting however that the fact that e6 has made it this far without succumbing to external pressure is mostly attributable to the steadfast philosophical stance of site administration and active contributors, something I doubt will change much anytime soon.
Updated by Millcore