I am hearing this afternoon that Acting Assistant Attorney General Richard Powers has announced that the Antitrust Division was restoring the 2015 Business Review Letter concerning the IEEE's IPR Policy. See this press release from ACT The App Association; there is also a write-up on Global Competition Review, though I can't access the full article because it's behind a paywall. I also haven't seen the formal statement from the DOJ-it's not up on the agency's website yet--but, if I am understanding the matter correctly, this is definitely a positive development. Last September, then-Antitrust Division head Makan Delrahim published a letter casting doubt on the DOJ's continued adherence to the 2015 Letter, as I noted (and criticized) here. It is to be hoped that restoration of the 2015 Letter will remove that doubt and, perhaps, facilitate further efforts on the part of SSOs to attain a more rational system for establishing FRAND terms for SEPs.
Update (4-16-2021): More from Florian Mueller here.