This is part of the US$ 25 billion buy back program Alibaba announced for their stock:
Hangzhou, China, March 22, 2022 - Alibaba Group Holding Limited (NYSE:
BABA and HKEX: 9988, the “Company”) today announced that the Company’s
board has authorized to upsize its share repurchase program to US$25
billion from US$15 billion (the “Share Repurchase Program”), in a sign
of confidence about the Company’s continued growth in the future. The
Company also announced that Weijian Shan, executive chairman of
investment group PAG, was appointed as an independent director to the
The Share Repurchase Program will be effective for
a two-year period through March 2024. As of March 18, 2022, the
Company had purchased a total of 56.2 million American depositary
shares under the previously announced share repurchase program, for a
total consideration of approximately US$ 9.2 billion.
Obviously, they do not go to the stock market and place a market order for 100 million shares, but make an offer to institutions to buy large amounts, and those institutions are now trying to get it done (by offering you or your broker or a partner of your broker an incentive).
Since "only" less than 10% of the stock is bought back, it makes sense that the offer value is not a lower bound for the stock (since not everyone can sell for that price). On the other hand, the offer price needs to be above the stock price, otherwise noone would sell.
The actual price has probably been defined some time ago, and the whole project has a time horizon until 2024, so daily price movements are not that relevant for their planings (but of course for your personal profit). It's (part of) the premium that Alibaba is ready to pay to get this large transaction done, and the institutions have their own ways of securing their deal and margin.
You are basically among the lucky 10%, and yes, it looks like it is basically free money if you just buy it back on the stock market.
You should check the conditions of the offer though. There may e.g. be a first-come-first serve condition attached (so it may run out, cause, well, it's free money), they may be allowed to lower/stop the offer at any time, or you may only get the money in september (so you would need to have the liquidity available now to buy it now). But it's also likely that there are no complications attached, as both sides get what they want - you some money, Alibaba or some intermediate institution their buy-back quota filled.