Terminal output messed up on Big Sur

I actually found out that the cause of the issue was this line tabs 4 in .zshrc. This worked on very well for me on Linux using Konsole terminal. I had copied my code configs from Linux after switching.

Update:

I found out that MacOS terminal uses negative values to the tabs command instead of positive. So for example, for width of 4 spaces, it should tabs -4. On Linux, it should be tabs 4 to achieve the same.

Such small config issues are difficult to diagnose and resolve. What might help is

• Rollback init files to last good version (e.g. by getting them from Time Machine)
• Start a shell without init files (bash --noprofile/zsh -d -f)
• Rename existing init files and rebuild them line by line