Execution permission should be removed from those files. I have a hazy memory from quite some time ago that an autostart script on my system refused to start until I removed the execution permissions from the .desktop file.
I just checked the permissions of the files in my ~/.config/autostart directory, all of which start successfully when I login. None are executable:
ls -lL ~/.config/autostart
total 40
-rw------- 1 scotty scotty 243 May 10 2024 feathernotes.desktop
-rw------- 1 scotty scotty 131 Dec 13 2023 iloggedinat.desktop
-rw-r--r-- 1 root root 1401 Jan 3 05:52 manjaro-hello.desktop
-rw------- 1 scotty scotty 340 Aug 28 2023 org.kde.yakuake.desktop
-rw-r--r-- 1 scotty scotty 190 May 8 2024 org.moson.matray.desktop
-rw------- 1 scotty scotty 135 Nov 10 2023 ytdlpbatchnew.desktop
-rw------- 1 scotty scotty 153 Nov 10 2023 ytdlpfolder2delaystart.desktop
-rw------- 1 scotty scotty 153 Nov 10 2023 ytdlpfolder3delaystart.desktop
-rw------- 1 scotty scotty 153 Nov 10 2023 ytdlpfolder4delaystart.desktop
-rw------- 1 scotty scotty 151 Nov 10 2023 ytdlpfolderdelaystart.desktop
If changing the permissions to non-executable doesn’t work, then you may need to completely delete those .desktop files, and re-add them (preferably via Plasma’s System Settings). I’m not sure what Plasma does when they are added, but I do know that the systemd-xdg-autostart-generator (which is included in the systemd package) should be adding them to the user’s systemd user id folder at boot/login.
For example, here’s my /run/user/1000/systemd/generator.late/ content (my last boot was 10 days ago, which is why they are dated Jan 15):
ls -lL /run/user/1000/systemd/generator.late/
total 84
-rw-r--r-- 1 scotty scotty 578 Jan 15 16:33 'app-at\x2dspi\x2ddbus\x2dbus@autostart.service'
-rw-r--r-- 1 scotty scotty 389 Jan 15 16:33 app-feathernotes@autostart.service
-rw-r--r-- 1 scotty scotty 474 Jan 15 16:33 'app-geoclue\x2ddemo\x2dagent@autostart.service'
-rw-r--r-- 1 scotty scotty 394 Jan 15 16:33 app-iloggedinat@autostart.service
-rw-r--r-- 1 scotty scotty 392 Jan 15 16:33 'app-manjaro\x2dhello@autostart.service'
-rw-r--r-- 1 scotty scotty 377 Jan 15 16:33 app-msm_notifier@autostart.service
-rw-r--r-- 1 scotty scotty 462 Jan 15 16:33 app-org.kde.discover.notifier@autostart.service
-rw-r--r-- 1 scotty scotty 388 Jan 15 16:33 app-org.kde.kdeconnect.daemon@autostart.service
-rw-r--r-- 1 scotty scotty 505 Jan 15 16:33 'app-org.kde.plasma\x2dfallback\x2dsession\x2drestore@autostart.service'
-rw-r--r-- 1 scotty scotty 382 Jan 15 16:33 app-org.kde.yakuake@autostart.service
-rw-r--r-- 1 scotty scotty 389 Jan 15 16:33 app-org.moson.matray@autostart.service
-rw-r--r-- 1 scotty scotty 478 Jan 15 16:33 'app-pamac\x2dtray@autostart.service'
-rw-r--r-- 1 scotty scotty 482 Jan 15 16:33 'app-pamac\x2dtray\x2dbudgie@autostart.service'
-rw-r--r-- 1 scotty scotty 472 Jan 15 16:33 'app-pamac\x2dtray\x2dplasma@autostart.service'
-rw-r--r-- 1 scotty scotty 486 Jan 15 16:33 'app-print\x2dapplet@autostart.service'
-rw-r--r-- 1 scotty scotty 466 Jan 15 16:33 'app-xapp\x2dsn\x2dwatcher@autostart.service'
-rw-r--r-- 1 scotty scotty 400 Jan 15 16:33 app-ytdlpbatchnew@autostart.service
-rw-r--r-- 1 scotty scotty 427 Jan 15 16:33 app-ytdlpfolder2delaystart@autostart.service
-rw-r--r-- 1 scotty scotty 427 Jan 15 16:33 app-ytdlpfolder3delaystart@autostart.service
-rw-r--r-- 1 scotty scotty 427 Jan 15 16:33 app-ytdlpfolder4delaystart@autostart.service
-rw-r--r-- 1 scotty scotty 424 Jan 15 16:33 app-ytdlpfolderdelaystart@autostart.service
drwxr-xr-x 2 scotty scotty 460 Jan 15 16:33 xdg-desktop-autostart.target.wants
Edit: if the autostart entries exist in your /run/user/[UID - eg 1000]/systemd/generator.late/ directory, then you can also check on their individual statuses by running:
systemctl status --user service-name-including-the-@-autostart.service