Month is 0 indexed, i.e. 0 represents January. When you pass in a string with explicit date formatting like "2022-5-31" the month is not 0 indexed.

> new Date(2022,5,31)
                ^
              June
                   ^ 
                   31 -> 01 of the next month (Jul)
< Fri Jul 01 2022 00:00:00 GMT+0430 (Iran Daylight Time)

> new Date("2022-5-31")
                 ^
                May
                    ^
                   31 valid day
< Tue May 31 2022 00:00:00 GMT+0430 (Iran Daylight Time)

This becomes explicit when you try putting days of 35, for example:

> console.log(new Date(2022, 05, 35));
< Tue Jul 05 2022 00:00:00 GMT+0100 (British Summer Time)

In the first example, January is 0 while in the second example, January is 1.

June only has 30 days so the extra 31st rolls over into July.