The first half of the equity line before 2020 was not part of the backtest done during the generation process of the strategy. This is the reason the Balance line does not look good before 2020. When you use a start date of 2020 for the generator / reactor you do not test the generated EA before that date as there is no reason to do so as you will not be trading the EA during that time period . What you want to do is to test he strategy in the future. For example, if the generator start date is 2020 and the end date is 2022 then the EA can be tested in a demo account in the months ahead to see how it works. This is why it is recommended for students to demo trade their EAs until they gain confidence in their ability to generate EAs that will result in future profits.
To help you gain confidence the EAs created by EA Studio and FSBpro are profitable I recommend you review my demo testing of the FTMO EURUSD EA here: https://eatradingacademy.com/forums/topic/ftmo-demo/