[Fermé] 504 error

While I am using elementor and I am trying to save/publish a page I get error 504.
I got the "technical issue" automatic email from wordpress locating the problem as
/home/customer/www/domainname/public_html/wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php. Code error: Allowed memory size of 805306368 bytes exhausted (tried to allocate 69632 bytes)
How can I address this?
I can also see that the database is huge, 220MBs, not sure if it has something to do with this.
Thank you