get_posts() function does not honor correct post type

This could be caused by a pre_get_posts action that doesn’t have the proper conditions/checks.

For example:

add_action( 'pre_get_posts', function( $query ) : void {
    if ( is_post_type_archive( 'tribe_events' ) ) {
        $query->set( 'post_type', 'tribe_events' );
    }
} );

Likewise if this was a page template and not a post archive they might have this in their theme template to force it to show only posts of that type:

add_action( 'pre_get_posts', function( $query ) : void {
    $query->set( 'post_type', 'tribe_events' );
} );

Both of these would cause the problem you described. Fixing them will be specific to that specific callback though.Checking $query->is_main_query() may help.

How to Fix It?

Fundamentally this isn’t a problem with your plugin, it’s something in the users site code, and they will need to find and identify this. The usual process of elimination of disabling things and checking will help, as will a search and code review of any pre_get_posts callbacks.