1/3 The risk may not only be for Tether (USDT) but for USD Coin (USDC). There is still no Dec 2020 attestation for USDC (see https://centre.io/usdc-transparency) and normally the accounting firm Grant Thornton issues the monthly attestation in the middle of the month following.
2/3 They are now more than two weeks late compared to their usual schedule. This is worrying considering that for the last attestation for 30 Nov 2020 ( https://www.centre.io/pdfs/attestation/grant-thornton_circle_usdc_reserves_20201216.pdf), the USD Coin held in custody accounts was 3,004,921,958 USD to back 3,002,021,340 USDC.
3/3 However since then the market cap of USDC as per https://coinmarketcap.com/currencies/usd-coin/ has more than doubled to 6,177,111,478 USDC in the past just over two months.