SHM (Smart Home Monitor) was discontinued with the classic app earlier this year.
The current similar feature is STHM (SmartThings Home Monitor.)
Just to be sure we’re all talking about the same thing…
FAQ: SHM and STHM are different
Nothing official has been said one way or another about what will happen to it once the groovy cloud is discontinued.
That said, I would agree with @Automated_House that it’s likely you could produce a similar tone with the new routines, and it would have the additional advantage of potentially running locally, depending on the device you use to create the tone.
What’s the brand and model of the device that played the tone?