A federal district court judge in Texas just struck down Biden's student loan forgiveness program on grounds that it constituted an impermissible exercise of legislative power:
"Whether the Program constitutes good public policy is not the role of this Court to determine. Still, no one can plausibly deny that it is either one of the largest delegations of legislative power to the executive branch, or one of the largest exercises of legislative power without congressional authority in the history of the United States."
https://thehill.com/regulation/court-ba ... f-program/
EDIT:
I am certainly no expert on administrative law, but I did take a course on it during my second year of law school. All in all, it was far too "fuzzy" an area of law for my taste (much like constitutional law, where the desired result too often dictated the legal analysis). The one thing I do recall very vividly was the overarching principle that the power of agencies--and this would include everything from the EPA to the IRS--derives its legitimacy entirely from some express congressional delegation of legislative authority.
Strangely, I don't recall any discussion of the issue of executive orders during that time (late 1980s), which would suggest to me that if executive orders were indeed being issued as frequently as they are now, they were, at least for the most part, being reserved for matters at least arguably within the executive sphere.