Ошибка подключения к базе данных

@fierevere

Здоровье сайта:

### wp-core ###

version: 5.4.2
site_language: ru_RU
user_language: ru_RU
timezone: +03:00
permalink: /%year%/%monthnum%/%postname%/
https_status: true
user_registration: 0
default_comment_status: open
multisite: false
user_count: 2
dotorg_communication: true

### wp-paths-sizes ###

wordpress_path: 
wordpress_size: 269,15 MB (282225066 bytes)
uploads_path: 
uploads_size: 336,25 MB (352581728 bytes)
themes_path:
themes_size: 37,34 MB (39157886 bytes)
plugins_path:
plugins_size: 73,84 MB (77431340 bytes)
database_size: 91,09 MB (95518720 bytes)
total_size: 807,68 MB (846914740 bytes)

### wp-dropins (1) ###

advanced-cache.php: true

### wp-mu-plugins (3) ###

Hostinger Change URL: version: 1.0, author: Hostinger.com
Hostinger Dashboard Notification: author: (undefined), version: 1.0
Hostinger Links: author: (undefined), version: 0.1

### wp-plugins-active (15) ###

Autoptimize: version: 2.7.3, author: Frank Goossens (futtta)
Contact Form 7: version: 5.1.9, author: Takayuki Miyoshi (latest version: 5.2)
GDPR Cookie Consent: version: 1.8.8, author: WebToffee
Google Tag Manager for WordPress: version: 1.11.4, author: Thomas Geiger
LiteSpeed Cache: version: 3.2.3.2, author: LiteSpeed Technologies
Popup Maker: version: 1.11.0, author: Popup Maker
Rank Math SEO: version: 1.0.44.1, author: Rank Math
Really Simple SSL: version: 3.3.4, author: Really Simple Plugins
Speed Up - Browser Caching: version: 1.0.6, author: Simone Nigro
Typing Effect: version: 1.5, author: 93digital
Under Construction: version: 3.80, author: WebFactory Ltd
Visual Composer: version: 28.0, author: visualcomposer.com
WebP Express: version: 0.17.4, author: Bjørn Rosell
WP Revisions Control: version: 1.3, author: Erick Hitter

### wp-plugins-inactive (2) ###

Akismet Anti-Spam: version: 4.1.6, author: Automattic
All-in-One WP Migration: version: 7.24, author: ServMask

### wp-media ###

image_editor: WP_Image_Editor_GD
imagick_module_version: Не доступно
imagemagick_version: Не доступно
gd_version: 2.2.5
ghostscript_version: 9.25

### wp-server ###

server_architecture: Linux 3.10.0-962.3.2.lve1.5.25.6.el7.x86_64 x86_64
httpd_software: LiteSpeed
php_version: 7.4.4 64bit
php_sapi: litespeed
max_input_variables: 5000
time_limit: 120
memory_limit: 256M
max_input_time: 120
upload_max_size: 128M
php_post_max_size: 128M
curl_version: 7.62.0 OpenSSL/1.0.2k
suhosin: false
imagick_availability: false
htaccess_extra_rules: true

### wp-database ###

extension: mysqli
server_version: 10.4.13-MariaDB
client_version: mysqlnd 7.4.4

### wp-constants ###

WP_HOME: undefined
WP_SITEURL: undefined
WP_CONTENT_DIR:
WP_PLUGIN_DIR: 
WP_MAX_MEMORY_LIMIT: 256M
WP_DEBUG: false
WP_DEBUG_DISPLAY: true
WP_DEBUG_LOG: false
SCRIPT_DEBUG: false
WP_CACHE: true
CONCATENATE_SCRIPTS: undefined
COMPRESS_SCRIPTS: undefined
COMPRESS_CSS: undefined
WP_LOCAL_DEV: undefined
DB_CHARSET: utf8
DB_COLLATE: undefined

### wp-filesystem ###

wordpress: writable
wp-content: writable
uploads: writable
plugins: writable
themes: writable
mu-plugins: writable

Что перепробовали:
LiteSpeed Cache
W3 Total Cache
WP Fastest Cache
WP-Optimize — Clean, Compress, Cache
WP Cloudflare Super Page Cache
Hyper Cache
WP Super Cache
WP REST Cache
Breeze — WordPress Cache Plugin
Simple Cache
WP Rocket
Cache Enabler
Speed Up
Browser Caching
WordPress Cache
Yasakani Cache

Сайт на хостингере, тариф предтоповый

@fierevere

Проблема в том, что даже после того, как мы вообще ВСЕ плагины отключили, ошибка не уходит.

Поддержка хостинга говорит, что у них все в порядке.

Я уже не знаю, что делать.

@vladvector

Сайт в процессе допиливания, на нем и пробовали.