Since there hasn't been data provided by TSR from the outage until now, but rather an overall data point, I used the old version of the 6/14 data compared to the 6/15 data and came up with these differences (from 6/14 15:00 UTC to 6/15 6:00 UTC)

1794 Horsea with 14 shiny

3136 overall "boosted" spawns with 24 shiny

Despite suggesting there's been no significant changes, it's gone from about an average of ~102 to ~128-131 just introducing that little bit of data suggesting either all researchers got bad RNG, or they've adjusted the shiny rates.

The data points from 6/14 15:00 UTC were: 2241 Horsea, 23 shiny (1 in 65 to 1 in 150) and 5750 overall boosted spawns with 55 shiny.

(edit) The TSR article: https://thesilphroad.com/science/go-fest-weekend-shiny-horsea-rate/