I agree with above post of Fore/Aft.
Are there any glass fibres in those holes? If not, it is a
repair done with a polystyrene based filler, ie Bondo, in Oz know as "car bog". Such products slowly absorb
water over time.
With so many 'filled holes' it looks like a previous blister
repair job, a failed attempt. Does not look a repair of an incident/collision etc.
Grind each of that bog out carefully, not to take any more good fibreglass out than needed. You can all fill it with a good
epoxy fairing compound, although I would fill larger holes with proper thickened epoxy and leave that just below the level of the
hull, as this stuff is hard to sand. And then before the epoxy is cured, apply an epoxy fairing compound, let that harden for a day before
sanding back.