Hi there, little late in the game but hope my comment helps at least for the state of mind. I got a Macbook Pro 14 M4 base model in July. I got a not so cheap LG 4k 60Hz monitor, it is a very quality monitor, it is even almost match my Macbook's display colors. But this screen goes black for a few sec like 2-3 sec thing, well I have it too. I tried the factory HDMi cable what comes with my montior, I bought a quality 8K Rode HDMi Cable. Same thing happend few times. Finally I bought a 2.1 Super High Speed HDMi 10k UHD 120Hz (its is even got Ethernet in it) from inakustik, very high quality, it was way over my budget back then but I wanted to solve this phenomenon. For weeks it was OK, no problem at all, no blackout. But after MacOS26 update the phenomenon came back. My monitor even flashes between orange and normal sometimes, like when you turn on and off TrueTone. What is interesting in this matter and I don't really saw anybody talk about this, but you can reproduce this "screen goes black for a 2-3 sec" thing in System Settings when you change your refreshing rate of you monitor, in my case from 60Hz to 50Hz or any other then back to 60Hz. Exactly the same thing happens every time you change the refreshing setting value. I also think this is not a hardware issue at all. This is some kind of software or HDMi communication issue between the Mac and monitors or cables. Kinda like it is refreshing the connection or communication but it goes black at the same time. If there is a hardver problem then it would get worse and worse but this isn't the case. Worth mentioning again that this thing happening with me on my M4 MacBook not even with MacMini. Sometimes nothing for a few days/weeks sometimes happen once or twice, and before Tahoe nothing at all. It is more of an annoyance or a phenomenon than a real hardver issues or fault.