Banks have like 10% or even less the dollars that they are supposed to be holding, but still are doing all fine.
Personally I don't think these tether conspiracy theories were ever true. Maybe they aren't 1:1 backed, but they have always been financially well off enough to keep the company running. And after the interest rates went up, they are probably making a killing. Typical bank has minimal reserves compared to them, and everyone is fine with that.
Reserve requirements are completely different from capital requirements. US banks are required to hold about $108 in assets for every $100 they hold in deposits, and their actual holdings are typically in the range of around $110 to $115 in assets per $100 of deposits. Central bank reserves are one type of asset that commercial banks can hold; a 0% reserve requirement just means that commercial banks can hold all of that ~$108 in other assets if they choose to.
In contrast, Tether has historically admitted to having as little as $100.20 in assets per $100 in liabilities [0], with a significant fraction of it in crypto and other assets that effectively wouldn't even count toward banks' capital requirements. It has probably dropped below $100 in assets per $100 in liabilities - i.e., been insolvent - at some point, and even taking its latest audit [1] at face value, it has far less capital than would be needed for a bank with the same asset profile in the US or other developed countries.
Personally I don't think these tether conspiracy theories were ever true. Maybe they aren't 1:1 backed, but they have always been financially well off enough to keep the company running. And after the interest rates went up, they are probably making a killing. Typical bank has minimal reserves compared to them, and everyone is fine with that.