I have definitely found paytm money the worst. They have absolutely no idea how bonds work, and randomly put up data in name of simplification.
I remember, last year a guy was complaining that he got sold a bond assuming he will get 30% yield.
There was typo in prospectus, and paytm money calcualted yield based on typo, without any real world knowledge of bond investing.
My problem is, making bond investing simple is difficult, as bonds are complex products. Besides most of them are long dated. You buy something because your platform showed you some fancy numbers in their dashboard. Only at or near maturity (which might be 3-5 years away) you realize that math did not math, like in the case you pointed out