Peroxide is an oxidant that can disolve some cellular walls , depending on concentration & cell wall structure. But the oxidant effect is short lived as the H2O2 molecule releases an oxygen atom pretty fast. So it's possible it could disrupt bacteria production temporarily. No idea for how long or to what extent.
I can't imagine it being dangerous under normal circumstances. Unless you're cleaning up a tank with huge nitrate levels, with poor skimming & large concentrations of peroxide & vodka for example. All bets would be off there.
Peroxide won't disturb the nitrifying bacterial filter either in a mature tank when doses at reasonable & sensible levels.