PHP error

Hello,
Please advise if this is an error or false positive:
PHP 8.0 incompatibilities:
FILE: sitemap-core.php
FOUND 1 ERRORS AND 0 WARNINGS AFFECTING 1 LINES
2206 | ERROR | Since PHP 7.0, functions inspecting arguments, like debug_backtrace(), no longer report the original value as passed to a parameter, but will instead provide the current value. The parameter “$last_mod” was changed on line 2198.