Fatal error: Maximum execution time

Hello,
I encounter the “Fatal error: Maximum execution time xxx seconds exceeded in xxx on line xxx” problem when I save a post or a page. I tried increasing the max_execution_time parameter to 900 but it keeps timeout.

If, on the other hand, I disable the plugin, everything works correctly.

Redis is up and running, through the ‘redis-cli monitor’ I see all the transactions but I noticed that they are not continuous, they are paused even for a few minutes and then they restart.

This is my “diagnostic”:

Status: Connected
Client: PhpRedis (v4.3.0)
Drop-in: Valid
Disabled: No
Ping: +PONG
Errors: []
PhpRedis: 4.3.0
Relay: Not loaded
Predis: Not loaded
Credis: Not loaded
PHP Version: 7.3.16
Plugin Version: 2.0.26
Redis Version: 5.0.7
Multisite: Yes
Metrics: Enabled
Metrics recorded: 1399
Filesystem: Working
Global Prefix: ""
Blog Prefix: 1
WP_REDIS_PREFIX: "--REMOVED--"
WP_CACHE_KEY_SALT: "--REMOVED--"
WP_REDIS_IGNORED_GROUPS: ["counts","plugins","users","userlogins","usermeta","user_meta"]
Global Groups: [
    "blog-details",
    "blog-id-cache",
    "blog-lookup",
    "global-posts",
    "networks",
    "rss",
    "sites",
    "site-details",
    "site-lookup",
    "site-options",
    "site-transient",
    "users",
    "useremail",
    "userlogins",
    "usermeta",
    "user_meta",
    "userslugs",
    "redis-cache",
    "blog_meta",
    "sitepress_ms"
]
Ignored Groups: [
    "counts",
    "plugins",
    "users",
    "userlogins",
    "usermeta",
    "user_meta",
    "WPML_ST_Package_Factory",
    "themes"
]
Unflushable Groups: []
Drop-ins: [
    "install.php v by ",
    "Redis Object Cache Drop-In v2.0.26 by Till Krüss"
]

What could be the problem?

I thank you