Operating under a pseudonym here, because the company is as vindictive as hell towards any current tutors speaking out. They get most bad reviews deleted from TrustPilot, for example, because they demand your email address if you leave one. No tutor is prepared to do that.
Please, I am currently a Maths tutor with GoStudent, I have been for a year.
The company is being run into the ground by greed on the part of the management. Tutors' wages are appalling (they'll charge you about 30 quid for just 50 mins for tutoring, of which the tutor gets just 13. Almost a 60% commission!)
The company has also just removed most of the bonuses that good tutors could once receive, we're even now expected to do ALL trial lessons entirely unpaid.
The communication between tutors and management is no better than you have found as a parent. You're right, WhatsApp communications have been removed, and they replaced it with their own "GoChat", which simply doesn't work. The old system of teaching over Zoom was also replaced with their own GoClass, which (especially if you use an iPad) also often doesn't work either.
When the tutors asked for a meeting with the company about pay last year, this was refused out of hand. We have also received no pay rise of any kind for two years, just constant removal of bonus schemes. The tutors feel undervalued, and are now starting a mass boycott of all trial lessons, starting in two days' time, in order to try and get some of these stupid and greedy decisions reversed.
I could say a lot more (such as about how they look to lock you into very long contracts) as someone who works for them, but I fear for my future work if I say too much here.
Go nowhere near this company. There are plenty of other tutoring platforms.