Red Bull are playing nice with Honda to get Tsunoda in for next season and workout a good deal for their takeover of Honda's engine department. I believe they're also moving their MotoGP sponsorship to Honda.
Red Bull has a reputation though for being like this with their junior drivers. Their burn rate is insane.
Klien, Liuzzi, Speed, Buemi, Alguersuari, Hartley, Vergne, Sainz and now it looks like Kvyat and Albon. A lot of these drivers have said its a high-pressure environment for young drivers and they are far too too eager to get rid of you so they can call the next guy up. Kvyat was extremely lucky to get a second chance.
Vergne took the criticism even further. When you sign with them you fall under their management and because of the way they control their branding, you couldn't bring your own sponsorship (until recently), so any pre-existing deals you may have had fall away. The result is once they discard you (and they are trigger happy), you have no management and no personal sponsors, so you have to rebuild yourself.