Here is how it might be:
As far as I can tell, there has always been an audio delay on the Vero 4k. At least there was on the dec/18 version. angry_sardine actually mentioned this here:
That was way before Kodi 18. And I can confirm, it was there, as I have now twice rerolled to the dec/18 Kodi 17.6 version. It might have been a bit less, which might just fit into the window of what you describe as not detectable and barely noticable.
So it might be that things just got that tiny bit inflated that makes people notice more… and as I said above, lipsync issues are a can of worms, once you open it, you really have a problem. I do not mean for the devs but for the users. Now people might have a closer look on the sync issue and might not be pleased what they find, I have to say that I am most not pleased atm. For the first time in two years I am actively looking for an alternative.
Why? Because with the measly 20€ box I once bought in China and libreelec Kodi 17.6 on it, I have no audio delay at all. Sure the box has its own problems and can‘t replace the Vero 4k but I wonder if something else can. Because having a 150ms audio delay randomly on video files isn‘t fun. If it were 100ms, it really might fall under non detectable… and that might have been in the past. But even if it that was true, the device would have danced a long time on the edge of non detectable to noticable.
And the issue would be a non issue if the audio delay would be global, but it just isn‘t. Sometimes it is there, sometimes not. And nothing is as annoying and frustrating to change settings for each file you play. Again, if the difference was 100ms max, it would also not matter but it matters with 150ms.
I hope the issue gets resolved because this is - at least for me - a real dealbreaker right now 