That's the basic clue on how reliable a casino is. With the basic issues that customers are experiencing and you'd see left and right complaints on different platforms, that's a red flag.
A good casino can easily address those issues with their support handling them all. Don't expect that only 1 of them are handling all of those hundreds to thousands of issues.
Because with how big the operations are, it should be made that they've got a lot of people and customer support to handle the problems of their customers especially the loyal ones.