If someone keeps cleaning up your mess, thank them, then learn where the mop is.

Repeated help can settle into an arrangement where one person does the work and the other stops seeing it. Gratitude matters and is not sufficient, because the pattern continues regardless of how appreciative you are. At some point the useful response is to learn the thing rather than to thank someone for it again.

Identify who has been covering for you and ask them to show you how they do it. Then do it yourself the next few times, badly if necessary, while they watch.