Unexpected PHP debug output when creating Child Theme for TT3

When using the Tools -> Child Theme configurator, on Step 3 I received the following message: The theme “Twenty Twenty-Three” generated unexpected PHP debug output:

Notice: ob_end_flush(): Failed to send buffer of zlib output compression (0) in /…../wp-includes/functions.php on line 5349

This is my first time creating a child theme in WP, so confidence is low. I checked around on support forums and found nothing; though I could have failed in the search parameters I used.

I did not continue to Step 4 as I’m not sure if this is an actual problem that needs solving for a child to be successfully created.

Any tips, be it links to reading up about it or straight up instructions are welcome. Thanks in advance.