utf_decode function depreciated

My website uses version 3-6-38 of JEvents. My hosting site seems to have just updated from php7 to php8 (they don't tell you because it is a free hosting service). Today I was trying to enter the JEvents configuration panel from the JEvents Dashboard. The site now has toatally crashed and just reports a string of 'Deprecated utf8_decode() messages' see here

: Function utf8_decode() is deprecated in
/home/vol18_1/epizy.com/epiz_32578370/htdocs/libraries/vendor/joomla/uri/src/UriHelper.php
on line
36

Deprecated
: Creation of dynamic property Joomla\CMS\Table\User::$id is deprecated in
/home/vol18_1/epizy.com/epiz_32578370/htdocs/libraries/src/Table/Table.php
on line
198

and it continues in a long string of likewise errors on many more lines ...

have a look here - http://lynvalleymission.great-site.net/administrator/index.phphttp://lynvalleymission.great-site.net/administrator/index.php

Now I know I am using an old version but I have had a lot of trouble getting JEvents working on my free hosting service so are reluctant to update but will a JEvents update fix this or is the error elsewhere?