Dividend charges?

Hi, Can someone experienced and knowledgeable please explain how dividend charges are calculated when trading indices. Primarily say FTSE100.

I opened a position shorting 6 indices of FTSE100, with usually has a spread of about 2 points with my broker (pepperstone UK)

About an 1 1/2 hrs later, they charges me -£124.92 shown as a dividend payment transaction which they withdrew. From a small account of 2k, that is over 5% fee on my balance of 2k. Pretty surprised as it seems very excessive!

Any info greatly appreciated. Thx

Of course, it is necessary to consider the terms of cooperation with each company individually, usually all this is written in the user agreement, because only in this way you will be able to properly assess the risks and make the decision that will lead to profits and a proper allocation of capital. I am against a person acting in the market without understanding what their actions will lead to.
But in general, yes, it looks a little strange because it is totally illogical, especially since you have distributed the capital correctly. If you notice something like that again, I think you should think about changing your brokerage company. Because with time it can lead to big losses.