If there is such a ceiling (clearly, I doubt it, seeing many of the main German industry leaders going down or offshore, so there is plenty space to grow), it is not of the EU's doing. It it about money and the advantages large incumbents have in our version of market capitalism.
DE still collects checks from global champions offshoring. Offshoring "fine" as long as money flows back to HQ. Allowing peripheral competitors to take your rent on the other hand less fine. The ceiling is EU's doing - it's EU legislation which does not allow member states to adopt the tier of subsidies/industrial policies to build competitors that can rival EU incumbents. Which can lose out to competitors with greater leverage (i.e. US), but unlikely to Poland. Of course cannot say it's impossible, but we have not seen case in modern economic history where global strategic champions arise without massive subsidies/protectionism, the type EU blocks within bloc to lock in existing hierarchy.