Ok, I found it.
You have a custom plugin (booking_mod.php) in which you are modifying table’s caption (which you call time range).
However this custom plugin has a deprecated function “BASE(‘front’)->format_start_end” which has been replaced with “wpb_format_start_end”. If you look at Query Monitor notices you will see what I mean.
Replace the line in your plugin and problem will be solved.
Next time if there is a custom function which is about the complained issue, please do mention about it.
Cheers,
Hakan