Hahaha suuure. I mean that's what the großaktionärs and their pathetic lobbyists tell you, so it has to be true, right? I mean, why would they possibly lie to you about something that makes them richer and all workers poorer?! The actual reasons why german wirtschaft suffers are not related in the slightest to Arbeitnehmerrechte. There are many reasons, here are just some of them:

HUGE lack of staatliche Investitionen (that's the main difference to the wirtschaftlich successfull states in the world). This is something that piled up during the last decades actually, because the former regierungs were even worse in this regard that the current one, basically destroying whole industries that could have had a bright economic future in this country. Instead, the current FDP dullis that run our Regierung mostly gift 39Mrd. to Unternehmen (by lowering their Steuers) which mainly benefit said Großaktionärs (who don't spend the money so it's not in the Wirtschaftskreislauf at all) and only lead to approx 11 Mrd. of private investments by those Unternehmen. So it would have been much more productive to invest that money directly as Regierung.
Dumb as fuck decisions by EZB to raise Zinsen through the roof (because they don't understand the difference between a temporary Energiepreis-Schock and Inflation), making private and public investments more expensive and thus hindering them.
Low wages leading to low Kaufkraft in Mittelschicht, leading to very little Konsum, which in turn becomes a problem for local Wirtschaft.
(Not a small point): External factors like china not buying as many cars from our zurückgebliebene Autoindustrie anymore (that completely fucked up by trying to milk their last century dampfmaschinen technology for ever, missing the anschluss)