Unusual Behavior Observed on several PCs

Here are four devices I have with their respective specifications and operating systems:

1. Desktop PC with an Intel Core i9-9900k processor, NVIDIA GeForce RTX 2060 graphics card, running Windows 11 Pro.

2. Multimedia PC with an Intel Core i7-4790K processor, NVIDIA GeForce GTX 1030 graphics card, running Windows 10 Home.

3. Laptop with an Intel Core i3 processor, Intel HD Graphics 5500, running Windows 10 Home.

4. Desktop PC with an Intel Core i7-7800X3D processor, NVIDIA GeForce RTX 4070 graphics card, running Windows 11 Pro.

The only common factor among these devices is my Microsoft account. However, I face the following issues on all four PCs:

Upon logging in, the language selector appears on the taskbar even though it is set to be hidden. I use English (US) as the operating system language and another language for my keyboard. When I log out and back in, the circle loading icon and cursor stutter, but eventually, I reach the desktop and the language selector disappears.

The second issue is random stutters, which occur sporadically on all four PCs. Additionally, the sign-in background is always black, even on the newest PC.

Account sync is disabled, and these problems started about two years ago on my first PC (PC1) before spreading to the others. While I had resigned myself to these issues, the recurrence of the problem on my latest PC (PC4) has become overwhelming.

I am hopeful that someone might have a solution to address these issues.