I don’t think a custom property is really a solution to tags. It would be great if proper tagging could be implemented.
Replies that suggest custom fields fundamentally midunderstand the nature of tags, their usefulness and how they are used.
Please add tags HubSpot, browsing this forum for 5 minutes clearly shows multiple requests for this feature dating back well over a year. Many of your competitors support this basic feature, it would be great if you chose to implement it.