We are seeing the same thing with v6.0.6. I have two sites now that I have upgraded and it completely crashes the front end of the site.
Seeing the following error:
[14-Dec-2022 15:59:47 UTC] PHP Fatal error: Uncaught Error: Call to a member function is_main_query() on null in /home/website/public_html/wp-content/plugins/the-events-calendar/src/functions/template-tags/general.php:1896
Stack trace:
#0 /home/website/public_html/wp-content/plugins/the-events-calendar/src/Tribe/Query.php(130): tribe_is_events_front_page()
#1 /home/website/public_html/wp-includes/class-wp-hook.php(308): Tribe__Events__Query::parse_query(Object(WP_Query))
#2 /home/website/public_html/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array)
#3 /home/website/public_html/wp-includes/plugin.php(565): WP_Hook->do_action(Array)
#4 /home/website/public_html/wp-includes/class-wp-query.php(1127): do_action_ref_array('parse_query', Array)
#5 /home/website/public_html/wp-includes/class-wp-query.php(1820): WP_Query->parse_query()
#6 /home/website/public_html/wp-includes/class-wp-query.php(3749): WP_Query->get_posts()
#7 /home/website/public_html/wp-inclu in /home/website/public_html/wp-content/plugins/the-events-calendar/src/functions/template-tags/general.php on line 1896
(END)