It may be majority of their support tickets, since many ports are a pretty crappy job. Does it start up? Let's ship it and call it a day. Sometimes not even that (see also Witcher 2 for Linux drama).
For many projects, if they would provide the same quality/effort for their majority platform, whey would go under.
And for the majority of tickets, I guess it is mainly tickets like "please have a Linux version, please have a Linux version that starts!".
I hate this company so much, so much assholes, because I have kid that wants to play that and that it is a shame to tell him that he can't because you want him to be on a Linux computer or otherwise he will boot on windows just for that!
In addition, with a few news we can see that they are a little bit okay to abuse of children or have children abused if they can sell more robux...
At this point, if they don't change their course, my only wish for this company is for them to crash and burn!