@dgodon that's a "yes, and" thing. If it's a "tax Big Tech and earmark it all for FOSS", while that sounds good, it's a bad idea, as it creates an incentive for the FOSS ecosystem to help to grow Big Tech profits.
More Big Tech profits, more tax money; more tax money, more funding for FOSS.
So these have to be decoupled into two separate things:
1. Serious financial support of FOSS by the EU (and the Member States).
2. Independently, taxing Big Tech, as that's the right thing to do anyway.