It would be nice to have a possibility to customize interface (at least, on desktop). For example, both text captions and icons on left panel are very small for me, even on 17" FullHD laptop screen. So, I guess I can say nothing about 13"@FHD screne on another laptop. And I guess it would be pretty unusable on 2k, 4k, 8k resolutions :(
The left items will be getting a sizable bump in size in the next release. They will also be usable on 4K, 8k assuming you scale the display properly :-)
Closing until a clearer problem is presented, currently we have options to configure the font of the posts separately from the rest. If you find this is unsuitable (because the icons don't scale) then configure your display scale under your DE's options.