Good point! From my experience, having different versions of third-party dependencies is a trade-off when having code in several repos. I've been in organizations where teams have needed to coordinate upgrades of things like logging & error handling tooling, to utilize the tooling across the services. If this would live in one and the same repo (and ideally in one reusable part of the code) it wouldn't be such a big thing.

Services living in a Polylith repo are deployed independently, that's a big part of the tooling support and how code is structured according to the achitecture.