Hallo docsuess84,
I also had problems playing 1080p on my Vero 4K after the update in May: There was a visible slowdown after some time, followed by skips. I opened a ticket and finally Sam Nazarko told me, that a bug was found and to be fixed. In fact, for me the problem was gone after updating to the latest version of the kodi v21 test release. The procedure is simple and described here:
https://discourse.osmc.tv/t/testing-kodi-v21-release-builds
Maybe you want to try that, too.
Kind regards,
Jörg