Do you even know why the pro-independence party (DPP) lost so badly in the local election for mayors? Because the people were disappointed in what DPP had done with the economy, not because they didn’t agree with the foreign policies DPP was pushing! (Please note that I’m not saying most people agree.) In local elections, people are going to choose whoever they believe would be the best for the city/county, not the one whose views on China they agree with.
Additionally, if you look at the latest opinion poll for the presidental election next year, you’d be surprised to find out that the candidate from the pro-independence party is leading.
Source: am Taiwanese
ps. you made a typo in your comment. it was the 2022 local election, not 2020.