Honeydak 12 Pieces Microfiber Detail Duster Sticks Mini Duster Crevice Cleaning Tool Car Air Vent Cleaner Fan Cleaning Brush for Home Air Vent Window The Smallest Spaces

My parents had a mark like this in their toilet and the only way I could get it out was manually scraping it off using a long stick covered in microfiber that I bought off amazon: https://www.amazon.com/dp/B09FYWG3HC?ref=ppx_pop_dt_b_asin_image&th=1 I think any long disposable stick would work; the tool I used was just what I had handy.