It's the most commented issue on their GitHub and it's basically ignored by Anthropic. Title mentions Max, but commenters report it for other plans too.
>>alexk6+(OP)
“After creating a new account, I can confirm the quota drains 2.5x–3x slower. So basically Max (5x) on an older accounts is almost like Pro on a new one in terms of quota. Pretty blatant rug pull tbh.”
>>Curiou+SF1
or (tested on Max x20 plan) when the subscription renewal fails by any reason (they try charge your CC multiple times) then you are still in for 2+ weeks till it dies