Photo credit: Wellcome Collection
This does not look like Pietro della Vecchia who painted in a much looser, painterly style. It seems more in the style of the anonymous master called Maestro della Fertilità dell'Uovo or Master of the Fertility of the Egg, see https://bit.ly/3yNDSgU and https://bit.ly/3zHaWs8 which depicts dwarfs, geese and lobsters hatching eggs from which small humans emerge. This artist was influenced by Flemish/Dutch genre art which can explain the earlier attribution to 'Dutch School'.
The Collection has commented: 'The attribution of this painting has long been discussed; not surprisingly, the proposed authorship has been suggested before, on the ground that eggs and dwarfs are involved in both. The collection has a dossier on this painting. It has been argued that there is a clear difference between this painting and those that have been brought to our attention attributed to Faustino Bocchi and the Master of the Eggs: the Wellcome picture shows a few large figures (relative to the size of the canvas) with lots of tiny infants, while the other two painters tend to show all their figures on the same small scale. Are there any paintings by Bocchi and the Master which also show monumental figures? Pietro della Vecchia had a number of styles and one expert thought this was a possible attribution for the Wellcome painting. There is also a painting attributed to Pietro in the Wellcome Collection https://bit.ly/3BFRTPg. However, all attributions are questionable, so the collection is happy to be involved in the discussion.'
Some of the "grotesque" paintings attributed to Pietro Della Vecchia that are referred to in the dossier are now available online at https://en.wikipedia.org/wiki/Pietro_della_Vecchia#/media/File:Pietro_della_Vecchia_-_Allegory_of_hearing.jpg and https://commons.wikimedia.org/wiki/File:Pietro_della_vecchia,_bacco_con_quattro_anziani,_1650_ca._03.jpg
To my eye, this picture is clearly closer to Bocchi and the Master of the Fertility of the Egg than to della Vecchia, who was a more mainstream and less esoteric painter. I think "circle of Faustino Bocchi," in which the Master of the Fertility of the Egg has been placed, or circle of the latter is reasonable.
Della Vecchia's grotesques seem to be more in the vein of those of Leonardo or Quentin Massys (like The Ugly Duchess at the National gallery), meaning they are less cartoonish or less like the work of a graphic artist, which is how the work of the Master of the Fertility of the Egg strikes me.