Why was my SL order executed even though the price did not breach my trigger?

At the moment, it is technologically unfeasible for a chart provided by a broker to show all the trades executed on the exchange every day.

There are millions of customers executing tens of thousands of trades on the exchange not just every hour but every single second. On a single stock, trades occur at microsecond intervals and even more on days that are comparatively volatile. The charts that you see on any broking platform are created using data feed that is released by the exchanges. The “ticks” in these feeds are nothing but snapshots that are merged consisting of several trades over larger intervals. For example, 1 to 4 times per second which means all the trades in a span of minimum 250 milliseconds. The charts are produced by means of those 4 ticks and not the thousand ticks or tricks that occur on the exchange.

Simply put, in no condition can the chart show all the trades.