For those of us who haven't followed the decision closely you're not offering a lot of insight here.
The Chevron decision is a precedent set by the Courts in the 1980’s in which when it came to adjudicating regulatory policies the courts would defer to the agencies expert knowledge in the subject matter. Many of the regulatory agencies operating under laws established by Congress have extremely complicated missions that require genuine expert level of knowledge to achieve their missions that are well beyond and outside of a Jurist legal expertise. So when it comes determining if a policy or regulation is necessary and legal the Jurist, per precedent set by the Chevron decision, defer to the Agencies expertise in that subject matter when it comes to things like policy, regulations, implementation and enforcement.
This has had the affect of having a stabilizing affect on Agency regulations and governance in particular as it makes standardization, implementations and enforcement of regulations consistent, predictable, understandable and effective.
Up ending the Chevron precedent is completely stupid, despite any legal or political argument, because that it does stabilize and standardize the regulatory process and makes it affective as policy decisions are based on actual subject matter expertise and not by a Jurist who has little to no subject matter expertise on the Agencies Acts (Laws) that the agencies have been tasked by Congress and administered by the Executive branch are required by law to adopt and enforce.
So now the regulatory mission of these agencies at both the State and Federal level can easily be upended at either level by a State or Federal level by a Jurist and thus the Jurist becomes the ultimate arbiter of policy for the agencies.
This will have an incredibly disruptive impact as now complying with law per Federal and State regulations will become chaotic as no one will predict or comply with regulatory requirements as they can be set or changed at any time or place by a Jurist without subject matter expertise.
So that right there alone is why it’s an incredibly bad decision. A jurist can make policy decisions based on legal or political ideology and not on expert knowledge. This is a recipe for bad governance and chaos and completely dismisses the very valid reasons that Chevron was adopted in the first place.
Not only that but it also is an violation of the separation of powers as the Courts will be essentially making law thus violating a right of Congress and will also set and administering policy which is a right reserved for the administrative branch.
This is not the first time that SCOTUS has over reached. The last two times was during the Civil War here Lincoln just out right ignored the Tanney Court until Tanney died and he replaced him with Salmon P. Chase. FDR took a different approach by putting tremendous political pressure on the courts during the Great Depression when a number of his programs were dismissed by SCOTUS by the means of changing the programs name and threatening to stack SCOTUS with more members who supported his national relief programs. He also brought tremendous public pressure on an isolationist SCOTUS at the outbreak of WWII.
Another idiotic thing about the decision is it’s a sword that can both ways. It just a matter of which party can control the WH and stack the courts with their ideologues. The reactionaries that would currently control SCOTUS won’t be there forever and the same applies to the lower courts and when the pendulum does swing the other way they will probably deeply regret this reactionary decision.