Is the return of Keynesianism a good idea?

Keynesians obviously welcome the return of Keynesianism to OECD countries: first, in the short term, massive support for household and corporate income during the crisis through fiscal deficits; then announcement of investment plans (in infrastructure, energy transition, R&D, training, building renovation, reindustrialisation), the objectives being to speed up the energy transition and to restore potential growth. Of course, the income support during the crisis has limited unemployment and corporate bankruptcies; of course, the principle of well-targeted public investment should be welcomed. But we should not forget the dangers associated with this policy: The risk that the return will be low on some of the public investments (transport infrastructure); The disruption resulting from excessive money creation linked to short-term financing of very high fiscal deficits; The need, once central banks stop monetising fiscal deficits, to increase the tax burden. Is it certain that the taxes that will be raised will not generate major distortions that would cancel out the beneficial effects of public investments? Are there “painless” taxes, especially in countries where the tax burden is already high? The risk, when central banks stop monetising fiscal deficits, of a rise in long-term interest rates if fiscal deficits are permanently higher (i.e. if there is reluctance to finance the entire increase in public spending through taxation). So it is to be hoped that governments will be able to identify the “right” public investment and the “right” taxes.