Long story, but lucid explanation!
One thing the RBI did on Friday was to tell banks: You need to keep 99% of your CRR requirements at all times.
A quick decode. If a bank has Rs. 100 of deposits, it needs to keep about 3% of it with the RBI as zero interest earning cash. That's the CRR. Every bank has an account with the RBI (like you have a savings account with your bank - your bank has an account with the RBI). That account should have this CRR every day. It's like a minimum balance.
A CRR is calculated on deposits that were, roughly, 15 days ago, and RBI says listen, just keep 3% of that number interest free for the next fortnight.
If a bank has a lot of money in their RBI account, they will take the "excess" (whatever's beyond CRR limits) and give it to the RBI as reverse repo, or SDF - basically like a very short term fixed deposit on which they earn interest.
But banks often see cash move around. You do UPI at midnight, and some money moves from your bank's account with the RBI to some other bank's account with the RBI. Your bank is like hello, I had this money and this uncle did UPI so i'm now short of money?
Now RBI knows this, so they say fine, listen, we will ask you that your AVERAGE balance over a fortnight should be 3%. But that doesn't mean you keep ZERO today and 6% tomorrow - that is a little too much. So banks get only a little headroom. They need a minimum of 90% of the CRR in their account every single day, and whatever they do, they should ensure the balances average to the full CRR averaged over the fortnight. That leeway of 10% allows a few of these midnight UPI uncles without CRR violations.
Now that I've confused you enough, here's more: What the RBI has done is that they've changed the 90% to 99%.
Banks, therefore, can't ever see less than 99% of their CRR needs in RBI at any time. Currently, as the screenshot shows, banks have about 96% parked as CRR (784K cr versus the requirement of 817K cr). Starting friday, they need to bump this up to 99%.
What does this do? Banks will probably keep more than 100% all the time because who knows which UPI uncle will transfer how much at midnight, boss. So banks earn interest on lesser money (CRR earns no interest for them)
Why has RBI done this? To reduce the overall liquidity in the system - banks are FLUSH with deposits after the FCNR scheme, and RBI is keen to ensure this doesn't cause the system to go overboard on lending. It controls the bank lending growth a little.
It will take out about 30,000 cr. in liquidity out of the system, and is likely to be a temporary measure while banks slowly grow into the liquidity overload. The impact is lower interest revenue for banks (marginally), but otherwise the measure should not meaningfully impact anything you and I see in daily life.
Long story for what isn't a big deal, I know, but I'm like that.