If you browse through trader forums you find posts about traders being blocked by their broker due to certain algos, e.g. Trading ticks with very many trades per day or performing arbitrage trading.

I tried to find documents from OANDA describing any kind of restrictions but did not find any.

Does that mean, that I am free to e.g. do broker arbitrage or am I just too stupid to find the matching paragraphs in their documentation?

Additionally: Some traders are posting that they have been blocked by their broker as soon they were too profitable. Fairy tale or truth?

Traders trading ticks with many trades per day are welcome with any broker. That's exactly the traders that brokers want.

Broker arbitrage is prohibited in some broker's business conditions, but it is difficult for a broker to detect and prove that.

Traders being blocked because they are too profitable is likely a fairy tale. Traders knowing to make profit won't trade with bucket shop brokers.

Sadly the bucket shop is the only affordable for many.