I think they meant it was "flawless" in terms of not being a degraded experience compared to Windows. Bugs will obviously still happen, but I'd also argue that the sheer breadth of the bugs they continue to squash over two years after the full game came out without having charged a cent for any new content that got released after the fact very well might be unparalleled by any other popular mainstream game. Over the summer, they released a set of fixes that included bugs like "one specific set of gloves were rendered poorly when worn by one specific race in combination with one specific set of armor[1]. When plenty of live-service games have much worse bugs than that they don't even get acknowledged for months at a time, it just doesn't seem useful to criticize a relatively small studio that's clearly going above and beyond to continue supporting a game with the only benefit for them being continued goodwill.

[1]: https://baldursgate3.game/news/room-temperature-fix-33-now-l...

Complete nonsense, of course there were bugs d'uh! But none of them had any major impact on anything and none of that has anything to do with the fact that the game ran flawlessly on Linux from day 1.