This page lists the main places where you can submit bug reports, ideas and other comments. If you want to suggest an idea or report a bug, it might already have been discussed somewhere, but duplicate suggestions or reports are okay.
The VVVVVV Discord has a #ved channel! You will probably get the quickest response here.
(More VVVVVV Discord info)
The repository has a section where you can create Issues, if you have a GitHub account.
You can report bugs and suggest ideas, and vote for others' reports or ideas here. Does not require account registration.
There is a board dedicated to discussion about Ved on the tOLP forum. Suited for discussion and questions, but also for suggesting ideas and reporting bugs, since topics can be marked as solved.