Stop buying from them if you don’t need them?
The problem is that a massive company essentially owns online commerce, anti-trust legislation should be addressing this and somehow it's not. Let them own a few % of the market, don't let them literally take over.
I understand your concern, but the reason that anti-trust legislation is not addressing this is that there is frankly no monopoly here.
[1] https://de.statista.com/infografik/16018/marktanteile-von-am...
The current percentage is almost irrelevant anyway, the endgame of this is monopoly whether or not they have it right now, the vertical integration of delivery alone is enough.
I'd split up the major supermarkets as well FWIW, but that's a different discussion.