Rule Machine used to have Restrictions, including Restrictions for Mode. These were done away with some time ago. You can see what these looked like by checking out Simple Automation Rule.
Why were they done away with?
The way restrictions work is that when the rule is triggered, or an app runs, the restrictions are checked. If a restriction is in effect, the rule exits and nothing happens. The important thing to note about this is that every possible restriction has to be checked every time the rule runs. While this is not a huge amount of computing to do, it is not zero. What we became aware of was that most rules didn't have any restrictions. But every rule was paying the price for there being the possibility of the rule being restricted. Most rules that had a restriction only had a single restriction, most often time of day or mode, but also a disable switch was common.
There was also a lot of confusion about restrictions and how they might interact or not with the actions of a rule. There were constantly questions here about 'why didn't my rule run', when it was clearly because it was restricted, although determining that meant a lot of digging in logs and events to show the user what had happened to cause the rule to be restricted.
With Rule 4.0 it became possible to implement a restriction directly in the actions of the rule. As shown above, a Simple Conditional Action that tests the restriction followed by Exit Rule does it nicely. The computational cost of such a Simple Conditional Action is roughly equivalent to the computational cost of the same test as a restriction, in fact many of them would use the exact same code (e.g. time restrictions). So this is clearly a preferable method of implementing a restriction. It becomes explicit rather than implicit, and each rule only pays for testing those restrictions that are relevant for that rule.
I can say that for the most part there has been much less confusion since restrictions were retired. The remaining bit of confusion is like yours, not having enough information to know how to implement a restriction as a conditional action. The original post that announced the retirement of restrictions gave examples of how to do each one. Here:
