Streaming video stutters

[DK]

Streaming video on amazon prime & Vimeo using firefox or google chrome stutters. The sound is fine but the video is lagging every 5-15 seconds for parts of a second. A video I tested is here:
https://vimeo.com/226053498

I found this while testing newer kernels on 20.04 on my Dell XPS 13 9310 2in1 (
11th Gen Intel i7-1165G / integrated graphics)

I tested several kernels:

5.6.0-1052-oem
-> works / no lag

5.8.0-43-generic
-> works / no lag

5.8.0-48-generic
-> works / no lag

5.10.0-1008-oem
-> works / no lag

5.10.0-1011-oem
-> not working / lag

5.10.0-1019-oem
-> not working / lag

Also tested a newer kernel:
5.12.0-051200rc6-generic
-> not working / lag

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-oem-20.04 5.6.0.1052.48
ProcVersionSignature: Ubuntu 5.10.0-1019.20-oem 5.10.18
Uname: Linux 5.10.0-1019-oem x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sun Apr 11 21:21:38 2021
InstallationDate: Installed on 2021-04-04 (7 days ago)
InstallationMedia: Ubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: linux-meta-oem-5.6
UpgradeStatus: No upgrade log present (probably fresh install)