As it happens Yes Bank they have given out a lot of bad loans which did not get repaid. That is the primary reason Yes bank is not doing great. Apart from this there are allegations of corruption against the top level executives of the bank. But mainly its the concern about the bank's balance sheet that has prompted RBI to act.
They are under because of a lot of shady practices like knowingly giving out bad loans, corruption and self dealing that enriched it's founder. He had been ordered by the regulator to step down 2 years ago, but that didn't prove to be enough to save the bank.
For example the founder and ex CEO was involved in a scheme where Yes Bank disbursed bad loans to a prominent business (Indiabulls) family, in exchange for which the family's business lent huge sums to Yes Bank's CEO and his children.
Beyond this Yes Bank loaned out several billions of dollars to companies that other banks were unwilling to lend. Most of that money never came back.
The Bank of England used to let employees have mortgages with the bank. Random people couldn't get a mortgage from the Old Lady but their employees could. It's a huge National Bank, giving some middle manager a $0.5M mortgage on a nice house for his family at a slightly nicer rate than commercially available is a cheap perk and no real threat to stability of a trillion dollar GDP economy.
But while it's different in quantity and character it sends the wrong message. The newly created First Bank of Elbonia sees this and figures it's fine to lend $500M (a tenth of tiny Elbonia's GDP) to their chairman who is coincidentally also the brother-in-law of their newly elected Grand President. The money is never paid back, Elbonia sinks into a swamp of corruption. Oops.
So the Bank of England stopped offering such perks. It's a shame, but it's like when you're looking after young kids. Maybe you'd just run across this road, but with kids watching we should walk to the proper crossing and do it by the book. No self-dealing.
Lending $500M without collateral seems like a completely different thing.
Even UPI had pretty low margins, and wasn't really making them much money to make up for the HUGE losses they had because of the bad loans.