why does my meeting url that used to work now show "No valid meeting ID"?

Meeting IDs will eventually expire and no longer be valid. Depending on the type of meeting and when it was last used, expiration can happen 30 days from last use, or 1 year from last use. This article goes into more detail about meeting expirations: https://support.zoom.us/hc/en-us/articles/201362373-Meeting-and-Webinar-IDs

Hope that helps and please make sure to mark the solution as accepted if this information is what you needed.