[OnePlus 6T  Questions & Answers] Shirotaku:
This didn't work :/ Do you have any other ideas but factory restetting my phone? :c

Newest logcat output:

<<< log_count = 47 >>>

[10-12 00:10:19.837 930:8207 I/ActivityManager]

START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 pkg=com.spotify.music cmp=com.spotify.music/.MainActivity} from uid 10305 pid 4086

[10-12 00:10:19.852 731:731 E/ANDR-IOP]

IOP HAL: Received pkg_name = com.spotify.music pid = -1

[10-12 00:10:19.856 930:8207 D/ActivityTrigger]

activityResumeTrigger: The activity in ApplicationInfo{689c795 com.spotify.music} is now in focus and seems to be in full-screen mode

[10-12 00:10:19.856 930:8207 E/ActivityTrigger]

activityResumeTrigger: not whiteListedcom.spotify.music/com.spotify.music.MainActivity/51386926

[10-12 00:10:19.859 930:8207 D/ActivityTrigger]

activityResumeTrigger: The activity in ApplicationInfo{689c795 com.spotify.music} is now in focus and seems to be in full-screen mode

[10-12 00:10:19.859 930:8207 E/ActivityTrigger]

activityResumeTrigger: not whiteListedcom.spotify.music/com.spotify.music.MainActivity/51386926

[10-12 00:10:19.864 930:11858 D/ActivityTrigger]

activityResumeTrigger: The activity in ApplicationInfo{689c795 com.spotify.music} is now in focus and seems to be in full-screen mode

[10-12 00:10:19.864 930:11858 E/ActivityTrigger]

activityResumeTrigger: not whiteListedcom.spotify.music/com.spotify.music.MainActivity/51386926

[10-12 00:10:19.890 930:1105 D/RestartProcessManager]

Update Total Launch Times :com.spotify.music

[10-12 00:10:19.890 930:1105 D/RestartProcessManager]

updateSelf : com.spotify.music, size : 12

[10-12 00:10:19.890 930:1105 D/RestartProcessManager]

Increase Total Launch Time : com.spotify.music, times : 6, index : 11

[10-12 00:10:19.890 930:1105 D/RestartProcessManager]

Last Running Package : com.spotify.music , start time 1570831819890

[10-12 00:10:19.947 2539:2539 I/PhoneStatusBarView]

isFullAndNotchEnabled() isFullMode=false pkg=com.spotify.music isCameraNotchIgnoreSetting=false, uid=10419

[10-12 00:10:20.013 3955:3955 D/MyAccessibility]

mForegroundPackageName = com.spotify.music ClassName com.spotify.music.MainActivity

[10-12 00:10:20.066 3955:3955 D/MyAccessibility]

mForegroundPackageName = com.spotify.music ClassName com.spotify.music.MainActivity

[10-12 00:10:20.112 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 2 lines

[10-12 00:10:20.212 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 4 lines

[10-12 00:10:20.312 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 4 lines

[10-12 00:10:20.817 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 12 lines

[10-12 00:10:21.505 14894:14894 I/chatty]

uid=10419(com.spotify.music) identical 3 lines

[10-12 00:10:21.539 3921:3921 W/RecentsView]

filterSelfTask: pkg= com.spotify.music, getPackageName= net.oneplus.launcher

[10-12 00:10:21.539 3921:3921 D/RecentsView]

applyLoadPlan: id=14321, cmp=ComponentInfo{com.spotify.music/com.spotify.music.MainActivity}, uid=0, locked=false

[10-12 00:10:21.648 930:1105 D/RestartProcessManager]

increase duration : 1732 for com.spotify.music

[10-12 00:10:21.995 14894:14894 I/chatty]

uid=10419(com.spotify.music) identical 1 line

[10-12 00:10:23.911 930:11858 I/ActivityManager]

START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 pkg=com.spotify.music cmp=com.spotify.music/.MainActivity} from uid 10305 pid 4086

[10-12 00:10:23.919 731:731 E/ANDR-IOP]

IOP HAL: Received pkg_name = com.spotify.music pid = -1

[10-12 00:10:23.922 930:11858 D/ActivityTrigger]

activityResumeTrigger: The activity in ApplicationInfo{689c795 com.spotify.music} is now in focus and seems to be in full-screen mode

[10-12 00:10:23.922 930:11858 E/ActivityTrigger]

activityResumeTrigger: not whiteListedcom.spotify.music/com.spotify.music.MainActivity/51386926

[10-12 00:10:23.924 930:11858 D/ActivityTrigger]

activityResumeTrigger: The activity in ApplicationInfo{689c795 com.spotify.music} is now in focus and seems to be in full-screen mode

[10-12 00:10:23.924 930:11858 E/ActivityTrigger]

activityResumeTrigger: not whiteListedcom.spotify.music/com.spotify.music.MainActivity/51386926

[10-12 00:10:23.931 930:3753 D/ActivityTrigger]

activityResumeTrigger: The activity in ApplicationInfo{689c795 com.spotify.music} is now in focus and seems to be in full-screen mode

[10-12 00:10:23.931 930:3753 E/ActivityTrigger]

activityResumeTrigger: not whiteListedcom.spotify.music/com.spotify.music.MainActivity/51386926

[10-12 00:10:23.932 930:1105 D/RestartProcessManager]

Update Total Launch Times :com.spotify.music

[10-12 00:10:23.932 930:1105 D/RestartProcessManager]

updateSelf : com.spotify.music, size : 12

[10-12 00:10:23.932 930:1105 D/RestartProcessManager]

Increase Total Launch Time : com.spotify.music, times : 7, index : 11

[10-12 00:10:23.932 930:1105 D/RestartProcessManager]

Last Running Package : com.spotify.music , start time 1570831823931

[10-12 00:10:24.010 2539:2539 I/PhoneStatusBarView]

isFullAndNotchEnabled() isFullMode=false pkg=com.spotify.music isCameraNotchIgnoreSetting=false, uid=10419

[10-12 00:10:24.088 3955:3955 D/MyAccessibility]

mForegroundPackageName = com.spotify.music ClassName com.spotify.music.MainActivity

[10-12 00:10:24.178 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 4 lines

[10-12 00:10:24.278 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 3 lines

[10-12 00:10:24.328 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 1 line

[10-12 00:10:24.819 14894:14986 I/chatty]

uid=10419(com.spotify.music) RenderThread identical 13 lines

[10-12 00:10:25.147 14894:14894 I/chatty]

uid=10419(com.spotify.music) identical 3 lines

[10-12 00:10:25.167 3921:3921 W/RecentsView]

filterSelfTask: pkg= com.spotify.music, getPackageName= net.oneplus.launcher

[10-12 00:10:25.167 3921:3921 D/RecentsView]

applyLoadPlan: id=14321, cmp=ComponentInfo{com.spotify.music/com.spotify.music.MainActivity}, uid=0, locked=false

[10-12 00:10:25.250 930:1105 D/RestartProcessManager]

increase duration : 1292 for com.spotify.music

[10-12 00:10:25.614 14894:14894 I/chatty]

uid=10419(com.spotify.music) identical 1 line

Edit: Ok, I didn't have this behaviour today. So it might be fixed. But if it isn't I'll factory reset my phone. Thank you for your help!

Edit2: Error is back. Gonna reset my phone later.