PlugBegin function in vimrc file not highlighted after reinstalling Vim

All works fine with Vim Plug but in the vimrc file the function PlugBegin and its contents are not highlighted like they used to be (it happens with any colorscheme).
It was working fine until I uninstalled Vim and re-installed it again. First I thought it was because I had to 'refresh' vim plug, so I did PlugUpdate and PlugUpgrade and they worked normally, but the highlighting problem persisted. Again, everything else is working normally.


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```
Vim v8.2.1801
Features huge.
```

- Type:
- [x] Bug
- [ ] Enhancement
- [ ] Feature Request
- [ ] Question
- OS:
- [ ] All/Other
- [ ] Linux
- [ ] OS X
- [x] Windows
- Vim:
- [x] Terminal Vim
- [x] GVim
- [ ] Neovim