Only the 1% is based on value, the .2 can be a fixed amount per lot so the tax rate can actually be a higher percentage while still being a lower bill with a lower purchace price.

200k home 1.8 rate=3600 yr (2k for value per prop 13 and 1600 total in voter approved bonds, csa, etc.)

same home sells for 400k a few years later, tax goes up to 4000 for value (1%) but 1600 stays the same for the bonds, etc. so the rate is now less than 1.8 (5600 tax on 400k home more like 1.4)

when it sells for 600k, tax is 7600, guess what 1.2 tax rate, so if it sells as a repo for 300k you want to use the 1.2 to figure the tax at 3600 but that wont be what it ends up, it will be 4600 (3000 for value plus 1600 fixed) so the rate isn’t always constant. prop 13 held taxed to 1% of the value plus any voter approved taxes (by 2/3 vote) above that and mello roos if applicable but they are not always value based, often based per dwelling. In my area, trash is included in property taxes but it is a fixed bill per house not value based, that is one example of fixed additions to the tax bill that can throw off the percentage theory, street lights can be another ($50 a year per house if they have them, free if it is an area that doesn’t have them). It is actually a more fair way to pay, just because you bought your house for more doesn’t mean you should pay more for trash, your share of the street lights or your cut of a school or sewer bond, especially if you don’t have sewer or street lights where you are.

You need to see the actual tax bill itemized to determine how much is value based and how much is fixed, assessor websites can sometime provide that info very easily.