Links Corrupt, Header, Menu, and Background Color Dissappeared

We use categories for the calendars on our website. After the last ‘My Calendar’ update, we now have display errors on the single event views in both of our calendars. The problem is especially noticeable starting in February, but exists in all months.

The links to these single events have changed and appear to be corrupt.

Here is an example link that is not anything like our normal links:
https://eckankar-utah.org/my-calendar/?cid=mc-38fa0a632c1e01fd39aa020176cacae3&embed=true&mc_id=1475

The link would usually look something like this:
https://eckankar-utah.org/my-calendar/?mc_id=1475

The website header and menu are no longer visible on the single event display – also, the white background that normally covers the page on not there. This allows the hero image from the home page to bleed through – looks pretty bad.

No new plugins have been added. The only change was the update.

None of the below efforts worked to remedy the issue:
Uninstalling and re-installing the plugin
Clearing website, browser cache and purging the entire domain cache
Tried re-saving permalinks trick
Double checked and re-saved calendar categories
Make new test calendar – but same results

Hope you can help us out.

************************************
https://eckankar-utah.org
https://eckankar-utah.org/utah-eck-public-events-calendar/
https://eckankar-utah.org/utah-eck-member-events-calendar/

Running: WordPress 5.6 and PHP 7.4

==My Calendar:==
Version: 3.2.12
DB Version: 3.2.12
URI: https://eckankar-utah.org/my-calendar/
CSS: twentytwenty.css

The page I need help with: [log in to see the link]