depends
While I hate posting here these days I can't let people set fire to their homes because of these things.
Let's compare what happens when you plug a USB charger into the wall, a C-C cable into and that cable into a USB C specification compliant laptop: the laptop asks both the cable the charger what wattage they are capable of and accordingly draws an appropriate amount of watts.
When you add this adapter, all the smarts are gone. The laptop might just happily overdraw both the charger and the cable. And while any charger worth a damn will have overdraw protection, cables do not have any such. USB C specification compliant systems are able to identify whether the cable is 60W or 100W maximum and won't draw more than that. These adapters are not specification compliant. If the laptop draws 90W or 100W over a 60W cable, it's anyone's guess what happens. While there certainly is some breathing room and I wouldn't be overly worried about drawing 65W over a 60W certified cable, overdrawing a cable by 50-67% is definitely worrisome.
So this adapter can be safe if