Most of wallets that are recommended above are closed source, so they are safe for now, but no one knows what will happen in the future, so if you do not plan to invest large sums or for long periods, they are fairly good.
you can also try -----> https://unstoppable.money/
But if you want to store a long time, it is better for you to transfer your stablecoins into cash, given that stablecoins (USDT) may not be stable in the long term.