Just as a two cents from someone who has witnessed their fair share of graduations recently, this statement reads a lot more like Yugo's situation than a simple contract renewal breakdown.
Nina and Mysta have both let their contracts run out and both of them were given ample time to announce their graduation and then have a final victory lap before they left. Ex-ID had graduation announcements for people that don't graduate until the end of October that are still active. Yugo, on the other hand, went missing for two weeks and was graduated after mutual agreement. Not terminated. Termination implies a company-initiated closure of a contract, whereas mutual graduation is similar to letting an employee hand in their letter of resignation so that they aren't stained by being fired outright.
Not allowing Magni and Ves to stream for 7 weeks before 'graduating' them with no graduation stream says to me that Cover probably wanted them out, but allowed them to get the ball rolling on a graduation/resignation behind the scenes so they didn't have to be forced out. Vtubers negotiate contracts all of the time but don't have their activities suspended until pen is put to paper, and 'honoring their wishes to graduate' doesn't mean there was no pressure to leave.
My opinion only has as much weight as anyone else's, but that's my take. They graduated because they had to.