Is this whole BETH/ETH market on Binance a scam?

Five weeks ago, I enquired with Binance about staking ETH. I have a reasonably large holding, and rewards are variable 5-20%, based on the market. I was told I can only stake 0.1 ETH per day, which made staking my entire amount unfeasible. Another option was to buy BETH with my ETH, for which I'd receive the same rewards, which is what I did. However, since then the BETH/ETH price has dropped from circa 0.95 to 0.93, and while I've seemingly only been paid 5% rewards on this staking, the shift in price means that I'd now get about 1% less ETH than I originally staked.

Firstly, I don't understand why the price of BETH/ETH should be tanking right now. There are two explanations - that many people are converting their BETH back to ETH - which seems unlikely while 2.0 is yet to go live for several months - or that Binance are manipulating the price themselves for their own gain - which would explain why they prevent you from staking more than 0.1 ETH per day, thus goading you towards the BETH/ETH market in the first place.

I'm not an expert though, so can anybody shed some more experienced insight into this situation?