Does Spicer v. McDonough / May 2026 M21-1 update on aggravation apply to cases already pending Board appeal?

I have an OSA-secondary-to-mental-health claim currently pending on the BVA Direct Review docket (filed Nov 2025). My case is built around 38 CFR § 3.310(b) aggravation — obesity as an intermediate step, per Walsh v. Wilkie.

I recently saw that VA updated the M21-1 manual on May 1, 2026 to implement the Federal Circuit’s Spicer v. McDonough decision, and that this update apparently clarifies that permanent worsening is not required to establish secondary service connection based on aggravation — described as a meaningful expansion from the prior standard.

My question: does this kind of change (a court decision interpreted through an M21-1 manual update, not a change to the actual regulation or rating schedule) apply to claims that were already filed/pending before the update? Or does it only affect claims decided after May 2026, regardless of filing date?

I understand the “whichever version is more favorable” rule for changed rating criteria (like when a DC gets amended), but I’m trying to understand if that same logic extends to a case where the underlying regulation hasn’t changed, but VA’s own guidance on how to interpret it has, following a court ruling.

Has anyone seen this applied at the Board level yet, or talked to a VSO/attorney who has?