The 5th Circuit court of appeals has already ruled similarly that the SEC's in house courts are unconstitutional, and that Congress can't delegate its legislative/judicial powers to the executive branch in that case under the separation of powers [1], a case that will likely be heard by the SCOTUS. By extension, if that is upheld, the idea is that this same principle could be applied to other executive branch administrative courts like in use at the NLRB.

[1] https://www.winston.com/en/blogs-and-podcasts/government-pro... "Fifth Circuit Holds That SEC’s Use of In-House Courts to Adjudicate Enforcement Actions Is Unconstitutional"