Banks currently have way too much money and not nearly enough collateral. For banks, having large sums of cash is a risk as banks operate opposite of us, they need collateral (i.e. treasury bonds) to keep their books looking good. Therefore 60+ banks are holding too much cash every day, and to keep themselves from defaulting/going under each day, they are parking their billions in cash at the Federal Reserve in exchange for a 24-hour borrowed treasury bond. This allows the banks at the end of each day to balance out their books with these borrowed bonds. Then after 24 hours the cash/borrowed bonds are transferred back, and the bank has to park their money back at the Federal Reserve for 24-hours again for some borrowed treasury bonds to balance their books again. The reverse repo is where banks can offload their cash if they have too much for a set amount of time. The Federal Reserve is essentially kicking the can down the road, keeping banks afloat 1 more day at a time.

tldr; banks need quality collateral (i.e. treasury bonds), but because the Federal Reserve printers go brrrrrr, banks have way too much money and there isn't nearly enough good collateral available. Too much cash and not enough collateral = banks go under & likely hyperinflation.

Great explanation here with some extra juicy information if you have 25 minutes to spare: https://youtu.be/fttA-rNRYG4

Banks giving money to the fed overnight at zero or very low interest to balance their books because they have too much liquidity. It's at a record high right now, 3/4 of a trillion dollars last I checked.