If you are using "every tick based on real ticks" mode with MT5 so your data is same as you are trading it with Metatrader 5 with your broker (because it is the broker's data for backtesting).
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Testing trading strategies on real ticks and the explanation is on this post.

Testing trading strategies on real ticks
- www.mql5.com
The article provides the results of testing a simple trading strategy in three modes: "1 minute OHLC", "Every tick" and "Every tick based on real ticks" using actual historical data.
hello
I am developing an expert adviser. I want to test it on strategy tester. on xauusd m1 timeframe. history quality is 100% but it seems candles data are not true.
where is the problem?
thanks in advance.