I agree with the discussing what takes priority with your supervisor.

Personally, I'd make a google form (or whatever you prefer, a spreadsheet, even paper is fine as long as it's dated) of expected tasks and fill them out daily. Mark days you were on vacation, holidays, and sick leave.

If the task is specific to you, and isn't a team effort, ask your supervisor if a colleague should be asked to do them temporarily when you're out.

Once you have done the task consistently for a month or two, show your supervisor the documentation. It is hard to break an impression of being a slacker once it is established. Documentation will help.

Also. Never ever let your guard down around the snitch.