How to help accessibility without more option?

been watching some activity on a project, as i have the issue too, and maintainer doesnt want to merge pr or add options to improve accessibility to his app (link below). is this possible to do in a reasonable manner? visual issues are the subject here

what also do you do in these cases about these people? somewhere like eff that can help?

maintainer also attack the contributor for them having discussion about the issue too

https://github.com/iSoron/uhabits/pull/848#issuecomment-798813704

here is more info but maintainer hid all comments even on topic ones to avoid bad publicity likely

https://github.com/iSoron/uhabits/pull/777

and a user said they had eye issues and have trouble with light and dark mode and it got locked

https://github.com/iSoron/uhabits/issues/843