[STDERR] isnt bundle

#1
In /var/log/httpd/domains/my.domain.error.log, there are many lines like this

2023-09-06 22:07:20.494638 [NOTICE] [872288] [52.167.144.222:55985:HTTP2-1#my.domain-443] [STDERR] isnt bundle
2023-09-06 22:06:02.562809 [NOTICE] [872288] [188.130.210.127:57479#my.domain-443] [STDERR] is bundle

Different IP addresses. The site is still working, but what is that? Any idea?
Thanks.
 
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