Hydrogen peroxide (H2O2) from the local shop (dilute, 2-3%) sometimes has a stabilizer to slow its breakdown rate and increase its "shelf-life", since we'd like to keep it around the house on our shelf for years, and the shop would like the option to keep it on their shelf for a while as well.
Examples of H2O2 stabilizers include acetanilide and sodium citrate.
This answer notes that the Soyuz spacecraft (the one with the now-patched hole) also has a "shelf-life" and this one is only about 200 days, for reasons explained there.
Is it known if the Soyuz spacecraft(s) docked to the ISS use chemical stabilizers in its H2O2 so that it can remain docked to the ISS for 200+ days?
(Note that the Soyuz's H2O2 is at a much higher concentration [82%] than what you can buy at your grocery store.)
More info about the situation: