I am using AMD systems - both my desktop and one of my laptops is AMD based and I cannot recognize what you describe - but I don’t use 6.6.
Current Linux 6.6 versions as of 2024-09-14T22:00:00Z
$ mbn info linux66 -q
Branch : unstable
Name : linux66
Version : 6.6.51-1
Repository : core
Build Date : Thu 12 Sep 2024 13:36:42
Packager : Manjaro Build Server <build@manjaro.org>
Branch : testing
Name : linux66
Version : 6.6.51-1
Repository : core
Build Date : Thu 12 Sep 2024 13:36:42
Packager : Manjaro Build Server <build@manjaro.org>
Branch : stable
Name : linux66
Version : 6.6.47-1
Repository : core
Build Date : Mon 19 Aug 2024 10:25:48
Packager : Manjaro Build Server <build@manjaro.org>
Apart from being LTS - is there any other reason to use the Linux 6.6?
Manjaro uses the kernel sources from kernel.org.
But not every addition or improvement to the mainline kernel gets backported to LTS.
What gets backported is not decided by Manjaro Team.
Therefore - if you have issues with the current LTS kernel - i.e. a specific ‘fix’ in the mainline kernel is not backported - your only choice is to move to the latest stable kernel - which is Linux 6.10.
Linux 6.10 as of 2024-09-14T22:00:00Z
$ mbn info linux610 -q
Branch : unstable
Name : linux610
Version : 6.10.10-2
Repository : core
Build Date : Sat 14 Sep 2024 11:44:32
Packager : Manjaro Build Server <build@manjaro.org>
Branch : testing
Name : linux610
Version : 6.10.10-2
Repository : core
Build Date : Sat 14 Sep 2024 11:44:32
Packager : Manjaro Build Server <build@manjaro.org>
Branch : stable
Name : linux610
Version : 6.10.6-10
Repository : core
Build Date : Sat 24 Aug 2024 16:39:12
Packager : Manjaro Build Server <build@manjaro.org>
If you are getting blackscreen - it could be related to system configuration.
Please see → Black Screen with Plymouth - Cause and Solution - #2 by linux-aarhus