I get what you’re saying, but there’s a lot more to separation of powers than this. You might be well aware of all this, but for those that aren’t, here’s a giant wall of text.

The executive branch’s powers are clearly defined and including acting as the head of the military, the head of foreign affairs, and the executor of the laws congress passes. It is quite restricted by congress in many ways. Of course, the executive branch has emergency powers and limited ways around the laws congress enacts, but that’s not the default and it is very much intended to be restricted by congress.

The executive branch also has room to make interpretations (create regulations) and to prioritize certain laws when they come into conflict.

This is what they’re doing here. They have weighed the laws (from congress) they are tasked with enforcing, which includes (a) specific immigration restrictions and (b) a variety of other ones that could impact their ability to execute the immigration restrictions (the “26” laws waived, including water and environmental protections). The DHS (an executive branch agency) has determined that (b) these 26 place an undue burden that prevents them from executing (a) the immigration restrictions, and is therefore temporarily waiving (b).

You can read the actual order here: https://public-inspection.federalregister.gov/2023-22176.pdf

Notice that it does not say it’s randomly waiving laws of its own accord without a law that it is executing. It is clearly referencing the statues (enacted by congress) that it is acting on. It is identifying that it is failing to execute some laws, but only so it can prioritize another one it has deemed more important for this specific action. It’s also become popular for the executive branch to use emergency decrees to act unilaterally, but these are supposed to be much more limited and a functioning judiciary/congress should hold the executive accountable when this happens.

What the executive branch is NOT doing here is very important too. It is NOT deciding it doesn’t want to do what congress says. Congress could rewrite the immigration law or any of the other 26 laws to change the way the executive branch executes them, if it feels the executive is implementing them wrong. And the judicial branch could easily weigh in on this if someone affected brings the case to them.