Both tyres (on the same day) and I’ve generally found tiny stones in them.
Yeah, your supposed to check tyres periodically and remove those before they work there way through and puncture!
. Its sounds like they are just well worn, hence rubber is thinner and hence become more susceptible to this type of puncture.
Beware some brands "tubeless ready" models, they often have lower TPI (threads per inch) rating as they think that if you've put sealant in them, being more puncture resistant doesn't matter. (60TPI vs 150TPI on the Rubino's)
I rate Conti GP5000's but they aren't a budget choice
BikeINN have the Rubino's in non tubeless at £23 each in 28mm which will fit* and give you tad more volume = comfort.
* just have a look at what clearance you have with the 25mm - you essentially near 1.5mm more each side which shouldn't be an issue as its specced for mudguards so wont have the ultratight clearances some of the older 2000-2010's bikes came with.