There are two possible workarounds which are popular in the community.
The first is to have your routine turn on a virtual switch, and then use that virtual switch coming on as the “If” in your IFTTT applet.
If you want to use a routine as the “that” there is a smart app in the marketplace section of the SmartThings mobile app specifically for that purpose. Again it uses a virtual switch. That smartapp has been around for a long time, so it uses the original SmartThings terminology of “home phrase” instead of “routine”, but they’re the same thing.
The second is to use core, which can connect to IFTTT through the maker service/channel. Core is much more complicated, but also much more powerful.
So like many use cases, there are a couple of different ways to do this with smartthings, it’s just none of them are easily discoverable unless you ask in the forums.