Why different prices on different brokers' platform?

Below is the closing price for the week (3 Dec - 7 Dec 2018).

On Oanda's platform,

Pair Bid Ask
EURUSD 1.13743 1.13843
GBPUSD 1.27204 1.27354

On IG platform,

Pair Bid Ask
EURUSD 1.13943 1.13980
GBPUSD 1.27311 1.27365

For EURUSD pair, Oanda's price is shifted 20 pips downward. This is strange right? Basically you can buy from Oanda EURUSD at price 1.13843 and then immediately sell to IG at price 1.13943 for an immediate 10 pips profit. What do you guys think? Broker trying to stop hunt on Monday opening with a gap opening?

Timing / Weekend Spreads. relax all is good.
simply IG pushed the weekend before them. or vic versa. means bothing. spreads. its just weekend spreads.

Take a look at Oanda price candle chart. For EURUSD, there is a huge 20 pips red candle on the last M1 candle before the market close. Just the last min, it plunged 20 pips. But on other platform, there is no such plunge. This abnormal behaviour is what triggered me to 'investigate' the discrepancy between prices on different platform. On most if not all other weekends, the spread of different platform though may vary but they (bid-ask spread) overlap each other. But here Oanda's spread range is below IG's spread. That is why I said you can buy from Oanda and sell to IG immediately for a 10 pips profit ... lol. If one broker's ask is below another broker's bid, you just open up an arbitrage opportunity (Though not that straight forward because you cannot buy from one broker and sell to another like for stock) which should not have existed.

There is discrepancy across trading platform i believe can be used to give you a trading edge.

wel if youve found an arbitrage op then go for it. ha not sure it could be done in time but hey have a dip tell us how it goes

Different brokers have different liquidity providers which provide them different pricing. And the pricing also includes broker's own profits in it, so.