I don't know if SNN-BRS will have had much of an impact on ORK-BRS.
It's now easier to get to DUB from Cork or Limerick than it is to get to SNN or ORK respectively considering the frequency of bus services and the much better roads to Dublin (and especially because there's no easy way to bypass Cork on the way from Limerick to Cork Airport).
Catchment competition between the two airports is largely confined to North Cork and Kerry nowadays.
From 2016 to 2017, there was growth of 27K passengers on DUB-BRS, so it won't be possible to tell any impact from SNN-BRS from general slowdown on UK growth in Dublin. The numbers will just get lost.