You may fix a major issue by adding vinegar to the toilet tank.

Properly using vinegar.
After it has been shown that using white vinegar in the toilet is a great way to clean it correctly, the next step is to demonstrate how to utilize the product. In addition to removing limescale and any lingering grime, vinegar may cleanse and polish surfaces.

A half-liter of vinegar, warmed over low heat but not boiling, may be used to clean the toilet bowl. Carefully pour the vinegar into the bowl, being sure to cover the walls as well. Next, use a toothbrush to clean the area, and lastly, flush the toilet.
More than just restrooms
Not only can the toilet itself be cleaned, but the tank may be as well. Do not flush the tank after adding white vinegar; instead, let it in overnight. Walls that have limescale or rust will be cleaned up using this. If there is any scale in the cistern tank, you may flush the toilet and clean the inside with vinegar the next day.