I just looked here in the Nextcloud PHP Serverinfo and found the info, that the max execution time seems to be 900 sec:
Version: 8.2.25
Memory limit: 512 MB
Max execution time: 3600
Upload max size: 128 MB
OPcache Revalidate Frequency: 2
Extensions: Core, date, libxml, openssl, pcre, zlib, bcmath, bz2, calendar, ctype, dba, dom, hash, fileinfo, filter, ftp, gettext, gmp, json, iconv, SPL, session, mbstring, pcntl, standard, exif, Phar, posix, random, readline, Reflection, imap, shmop, SimpleXML, soap, sockets, sysvmsg, sysvsem, sysvshm, tokenizer, xml, xmlreader, xmlwriter, zip, mysqlnd, cgi-fcgi, imagick, curl, gd, mysqli, PDO, pdo_mysql, xsl, sqlite3, intl, sodium, ldap, tidy, pdo_pgsql, pdo_sqlite, igbinary, redis, ionCube Loader, Zend OPcache