see my screenshot https://i.imgur.com/iFFfthW.jpg (icon sizes and pixelation differ quite enormously) maybe time to make scalable icons? like SVG with icons not loosing quality when resized
my pc is windows 10 pro
screen resolution 4k with 150% scaling (see here https://i.imgur.com/96TB7Rt.jpg )
my monitor is 28inch
Steps to Reproduce:
1. set 150% scale, 4k res, 28inch monitor
2. open calc
3. look at icons on top
pixelated weird icons
normal looking, nice icons
User Profile Reset: No
windows 10 pro latest
For OP could you please clear icon cache  (or reset user profile) and retest.
We saw similar at 6.2.0 as in bug 119020
 the scaled PNG bitmaps each icon theme is cached in a folder in %appdata%\LibreOffice\4\cache\ simply delete. It will be rebuilt next launch.
I did so, deleted all in %appdata%\Roaming\LibreOffice\4\cache
when i restarted calc, it loaded a bit (obviously)
but i do not think that you meant that this will fix it, icons look still different (widened/pixelated) on 4k screen with 28inch.
You can see the difference, i have a 2nd screen with 1080p, 23inch, see below the differences..
you can clearly see pixels sticking in my face :)
i think i hope i have brought more light into the issue
Please try any SVG icon style available under Options->LibreOffice->View.
(In reply to Mikula Beutl from comment #2)
> I did so, deleted all in %appdata%\Roaming\LibreOffice\4\cache
> when i restarted calc, it loaded a bit (obviously)
> but i do not think that you meant that this will fix it, icons look still
> different (widened/pixelated) on 4k screen with 28inch.
> You can see the difference, i have a 2nd screen with 1080p, 23inch, see
> below the differences..
> you can clearly see pixels sticking in my face :)
> i think i hope i have brought more light into the issue
Your initial screen clip-- https://i.imgur.com/iFFfthW.jpg -- shows corrupted RGB channelization on scaling. That was bug 119020 -- happy if that has not returned!
Otherwise for HiDPI monitors as Mike K notes, try one of the SVG icon themes,e.g. 'Colibre (SVG)', from Tools -> Options -> View 'Icon style:' drop list.
The SVG icon themes are how we support HiDPI requirements.
Still an issue? Tried an SVG icon theme?
You could also test with the Skia backend in a dev build: https://dev-builds.libreoffice.org/daily/master/current.html Take one from Win-x86_64@tb77-TDF
Tools - Options - LibreOffice - View - Use Skia for all rendering
Set to NEEDINFO.
Change back to UNCONFIRMED, if the problem persists. Change to RESOLVED WORKSFORME, if the problem went away.