Hi M. Stefano,
To try and remove this being a specific plugin issue, these are the plugins I have installed:
Donation thermometer
DSGVO snippet for extensions leaflet map
Email address encoder
Events manager
Fluent Forms
Fluent forms pro add on pack
Happyfiles pro
Leaflet map
Litespeed cache
Meta Box AIO
XML Sitemap Generator for Google
Do you have any of these installed?
Thanks.