The Support Program has been discontinued, yes. Tapastic is encouraging the use of Patreon instead.
Thing is, the Support Program was always in beta from the very beginning, so it wasn't a certainty that it would be around for the long term. And according to the staff, the Support Program just didn't have a place with their new business model/system for Tapastic (especially with the new app and the coins system and such, which seems to also be in beta as far as I know, as the only series that get to lock episodes, only unlocking with the use of keys, are ones that would typically be series offered on Premium - you'll notice that Premium isn't around anymore either because of this; I don't know if the keys thing will be available to all creators down the road or only those who would typically be eligible for Premium, this is something the staff would have to answer).
Either way, the Tapastic Support Program is unfortunately gone, and there are no signs of it returning, at least not anytime soon :/ You can join the Tapastic Ad Revenue program though if you have enough subs (I'm not sure what the prerequisite is for Ad Revenue though, I think it's between 600-1000 subs, again you'd have to clarify with staff). Other than that, if you want a funding platform that works on the same "rules" as the Support Program, Patreon is your best bet.