Warning: Cannot modify header information on Activation

When I activate this theme (on a WP 6.3.1 Multi-site), I get the following messages:

Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /home/johnp/public_html/wp-content/themes/bravada/cryout/prototypes.php on line 412

Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /home/johnp/public_html/wp-content/themes/bravada/cryout/prototypes.php on line 433

Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /home/johnp/public_html/wp-content/themes/bravada/cryout/prototypes.php on line 433

Warning: Cannot modify header information – headers already sent by (output started at /home/johnp/public_html/wp-content/themes/bravada/cryout/prototypes.php:412) in /home/johnp/public_html/wp-admin/includes/misc.php on line 1431

Warning: Cannot modify header information – headers already sent by (output started at /home/johnp/public_html/wp-content/themes/bravada/cryout/prototypes.php:412) in /home/johnp/public_html/wp-includes/functions.php on line 6935

Warning: Cannot modify header information – headers already sent by (output started at /home/johnp/public_html/wp-content/themes/bravada/cryout/prototypes.php:412) in /home/johnp/public_html/wp-admin/admin-header.php on line 9