Forex rebate programs

Could anyone explain how does it work? Why some company (not my broker) are ready to pay some percentage of spread back?
Sounds so good to be truth...
Are there any impact to my trading?

Brokers invest for advertisement. The rebate program is just a type of marketing. In this case, the broker would have an agreement with someone/company to introduce them clients and in return someone/company would receive a small part of spreads/commission from the broker. Due to many introducing brokers around, some introducing brokers would give back a part of their share of rebates to the client in order to entice clients to register through them instead of others.

why brokers just not reduce the spread? it would be the best selling point?

if they reduce the spread, brokers will have nothing to offer to their introduce brokers right

Exness thave a very good offer , it has a very profitable social traders your can refer friends they make profit and you get cashback that is the link of social trading https://social-trading.exness.com/a/pm8fdhuq