While investigating another issue on my instance I noticed that when using strace I see a lot of composer autoload.php files not found, such as:
access("/var/www/nextcloud/apps/notes/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/notes/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1885, ...}) = 0
access("/var/www/nextcloud/apps/notes/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/notifications", F_OK) = 0
access("/var/www/nextcloud/apps/notifications/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/notifications/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1402, ...}) = 0
access("/var/www/nextcloud/apps/notifications/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/oauth2", F_OK) = 0
access("/var/www/nextcloud/apps/oauth2/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/oauth2/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1040, ...}) = 0
access("/var/www/nextcloud/apps/oauth2/composer/autoload.php", F_OK) = 0
access("/var/www/nextcloud/apps/onlyoffice", F_OK) = 0
access("/var/www/nextcloud/apps/onlyoffice/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/onlyoffice/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=2247, ...}) = 0
access("/var/www/nextcloud/apps/onlyoffice/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/password_policy", F_OK) = 0
access("/var/www/nextcloud/apps/password_policy/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/password_policy/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=677, ...}) = 0
access("/var/www/nextcloud/apps/password_policy/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/privacy", F_OK) = 0
access("/var/www/nextcloud/apps/privacy/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/privacy/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1210, ...}) = 0
access("/var/www/nextcloud/apps/privacy/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/provisioning_api", F_OK) = 0
access("/var/www/nextcloud/apps/provisioning_api/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/provisioning_api/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1523, ...}) = 0
access("/var/www/nextcloud/apps/provisioning_api/composer/autoload.php", F_OK) = 0
access("/var/www/nextcloud/apps/qownnotesapi", F_OK) = 0
access("/var/www/nextcloud/apps/qownnotesapi/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/qownnotesapi/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1796, ...}) = 0
access("/var/www/nextcloud/apps/qownnotesapi/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/recommendations", F_OK) = 0
access("/var/www/nextcloud/apps/recommendations/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/recommendations/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=820, ...}) = 0
access("/var/www/nextcloud/apps/recommendations/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/serverinfo", F_OK) = 0
access("/var/www/nextcloud/apps/serverinfo/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/serverinfo/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1023, ...}) = 0
access("/var/www/nextcloud/apps/serverinfo/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/spreed", F_OK) = 0
access("/var/www/nextcloud/apps/spreed/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/spreed/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=4499, ...}) = 0
access("/var/www/nextcloud/apps/spreed/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/survey_client", F_OK) = 0
access("/var/www/nextcloud/apps/survey_client/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/survey_client/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1158, ...}) = 0
access("/var/www/nextcloud/apps/survey_client/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
access("/var/www/nextcloud/apps/systemtags", F_OK) = 0
access("/var/www/nextcloud/apps/systemtags/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/systemtags/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1215, ...}) = 0
access("/var/www/nextcloud/apps/systemtags/composer/autoload.php", F_OK) = 0
access("/var/www/nextcloud/apps/tasks", F_OK) = 0
access("/var/www/nextcloud/apps/tasks/appinfo/info.xml", F_OK) = 0
stat("/var/www/nextcloud/apps/tasks/appinfo/info.xml", {st_mode=S_IFREG|0644, st_size=1727, ...}) = 0
access("/var/www/nextcloud/apps/tasks/composer/autoload.php", F_OK) = -1 ENOENT (No such file or directory)
Indeed those files do not exist but checking git they do not exist in the repositories of those apps either. I wonder why those files are called and by what (I guess client). I did not want to make github issue of this yet as I think the answer probably can be done by some community folks around here. I would apreciate some clarification on this one.