Is this just a hidden way to raise money without calling it another round? An effort to avoid the appearance that you are burning way tooo quickly with added bonus of making employees happy and attracting talent?

What stops founders, major investors, or even the company itself from selling shares in a tender offer and reinvesting it back in the company?

Or, to put it another way, is the rise in tender offers actually a indication we're getting closer to the bubble bursting?