This issue can be caused by a mandatory access control mechanism (MAC, such as SELinux) that restricts your Nginx process from establishing connections to port 80.
For example, Fedora and RHEL/CentOS come with SELinux enabled by default and there the (counterintuitively named) SELinux boolean
httpd_graceful_shutdown controls whether Nginx (or any other web-server) is allowed to connect to port 80.
Since Fedora 27 (and thus RHEL 8 I presume),
httpd_graceful_shutdown is disabled, by default. Thus, one has to explicitly enable it (e.g. with
setsebool) when OCSP stapling is configured in Nginx.
When it’s disabled on Fedora, Nginx logs subsequent OCSP errors like this:
2020/08/20 22:00:04 [crit] 39288#0: connect() to [2a02:26f0:eb::214:bd5a]:80
failed (13: Permission denied) while requesting certificate status,
(with SELinux, there is also a
name_connect AVC logged by the system)
Note that my example differs slightly from yours, i.e. different syscall and errno value. Thus, it looks like you are using a different OS with perhaps another MAC security mechanism.
See also: related thread with some more details in the Fedora Discourse instance