copy & paste always not workign well

Does it work from the menu: Edit > Copy?

If so, your issue is with the modifier keys.

Does it not work at all?

If so, your isse is with the clipboard.

THere are third party apps that interfere with the clipboard and there are third party apps that interfere with the clipboard.

Modifier keys:

• WhatsApp on the web being the active tab in the browser
• WebRoot
• Apple Terminal 
• Word, Excel, Powerpoint
• »Enable Full Keyboard« in Settings > Accessibility > Keyboard on Mac OS
• »Keyboard Navigation« in Apple settings > Keyboard 
• Apple Mail, Outlook
• Spacebar is used as a shortcut by the system
• Chrome, Internet Explorer, Safari
• Wacom Desktop Center, Wacom settings
• Windows Touch Pad problem
• LastPass, Bitwarden (password managers)
• The VPN
• LangSwitcher app (it needs to be closed and disabled)
• Notes

clipboard:

• Parallels Toolbox running with the Clipboard History
• LogoTech Keyboard management software
• TeamVewer Clipboard > Use Shared Clipboard
• Apple iOS device simulator from Xcode
• Windows Multi-clipboard
• Windows Clipboard History
• Clippy
• Chrome Remote Desktop
• Mouse Pointer Highlighter
• AnyViewer
• Pastebot app
• Overzealous antivirus (Digital Guardian) as well as viruses that empty the clipboard
• Vector Magic
• Keyboard Maestro with Clipbboard History
• Clipboard apps named »Paste« and »Ditto«
• Windows 11 Multi-Clipboard
• Deepl translator app
• AMD Software Host Application 
• An app called »Get Plain Text«

Both lists are most probably not complete