Ironic that people buy it for streaming media (pirated or not), but RPi is terrible for video playback.

I have an RPi4, tried kodi (libreelec OS) and vlc on raspbian, both apps stutter with most videos at 1080p. Luckily I repurposed it for IOT so I'm pretty happy with it.

It really depends on the codec support. The Pi4s have hardware support for H.265 (4Kp60 decode) and H.264 (1080p60 decode).

I have issues with VLC showing a black screen when the (H.265) video is maximized. Would you by any chance know what the issue is ?

VLC probably doesn't use the hardware decoders. Linux video acceleration is a mess, and without the exact correct versions of every component, it doesn't work and will fall back to slow software.

Hardware decoders tend to be picky about the exact video format. VLC wants to work with anything, which also makes it not a good idea to use the hardware decoders.

Even Chrome on Linux doesn't use hardware acceleration on any GPU for video.

I’m afraid not. My skills are limited to reading the spec sheet. Most likely this is a software issue.

You may have had your gpu_mem setting too low. As I recall the default values were problematic on the 4. Even I had a problem initially, and I have one of the models with 4GB. These days the image libreelec provides should work fine (at least that's what I'm using without any problems).

That's not usual. Are you sure you had hardware decoding working?