It is the HSA tax form, and yes — you must file it in any year you contribute to or withdraw from an HSA, even if the whole thing was routine.
Form 8889 is where your HSA activity gets reported. You must file it with your return in any year you contributed to or took a distribution from an HSA.
It has three parts:
Part II line 15 is where the shoebox strategy shows up. You report qualified expenses, not expenses-incurred-this-year — a distribution reimbursing a 2019 receipt is qualified in the year you take it.
Skipping the form when you had a distribution is the fastest way to have the entire withdrawal treated as taxable.
Walkthrough: Form 8889 Explained